Runs rough, rich error, high fuel pressure

1995 GMC JIMMY
90,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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ROBERT CURTISS
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I am working on the vehicle listed above that was sitting in a garage for two to three years.

Battery was replaced and then the fuel pump since the old one was not providing any fuel plus, once I got to it, one of the hose connections had rusted through.

It now starts, but rough. Service engine soon light blinks after a couple minutes (running rich). Liquid which seems like just water comes from the exhaust. I have not been able to get it up to temperature since I started this.

Fuel pressure was checked, after fixing a bum gauge. Using the pigtail on the side wall to run the fuel pump, I am getting 70 psi, 66 or so when running. The fuel pressure does not hold when the pump turns off. I opened up the intake and expected to find a leak but I did not. I still replaced the regulator, but not the entire spider. I crimped hoses and neither stopped the bleed down of fuel pressure, but crimping both seemed to slow it down.

No leaks seen anywhere in the fuel line. I even pulled out each injector to look for leaks, none found.

I replaced the cap, rotor and plugs, the wires look brand new.

When it runs, there is a 'tick' that is in relation to RPM (higher RPM = faster ticks).

The fuel pump was not an AC Delco, but the chain store's stock. I am not confident in the fuel pressure gauge.

I have not touched the fuel filter because the pressure is good. I know the gas is old, but seems like it shouldn't be this rough.

Ideas? I am considering the following: spider (just because it fails all the time, but I have already replaced the FPR). Maybe a faulty fuel pump? Other?
Aug 1, 2018 at 2:46 PM
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STEVE W.
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I would try a different gauge for the pressure as it is possible yours is reading wrong, however as it leaks down fast the check valve in the pump is faulty and that will cause starting issues even if the pressure is okay. The old gas is not going to help the situation, especially if you are in an area where ethanol is added to the fuel. You might want to drain the tank and dump in some fresh gas before you start tackling the rest as it could easily cause rough running depending on the amount of water it has absorbed from the air.

Aug 1, 2018 at 4:09 PM
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PATENTED_REPAIR_PRO
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What about rust inside the fuel line both blocking fuel flow and causing a too high fuel mixture because of the excess fuel pressure?
Aug 1, 2018 at 4:35 PM
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STEVE W.
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I suppose the return line could be plugged or damaged but even then this new pump has an issue because if the return line is blocked the check valve should still retain the higher pressure. Easy way to test that would be to disconnect the steel return line at the fuel nut on the rear of the manifold and run a simple rubber line back into the tank filler. If the pressure drops and it runs better then replace the line. However, I would also expect fuel flow problems from the filter being blocked if it is rust. (Fuel filter is on the frame rail under the drivers door).
Aug 1, 2018 at 7:19 PM
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ROBERT CURTISS
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I have done 'pinch' tests on the rubber fuel hoses near the fuel filter. I believe I am pinching it enough (with vise-grips) to seal the hose, but still getting a slow bleed of pressure. I have done this with both hoses (pressure and return). I have looked all over for a leak and cannot find one.

I rented the fuel gauge from a local parts store. I will return it tomorrow and rent another from a different store just to be sure of the specs I am getting. 70 psi with power from under the hood, then instant drop to 60, then slow bleed within two minutes to zero.

Aug 1, 2018 at 7:24 PM
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STEVE W.
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Instant drop to 60 will be the regulator bleeding off. The slow bleed to zero is the check valve in the pump. It holds the pressure in the system to provide faster starts on a hot engine. The primary symptom seen with a bad one is that you need to turn the key on/off a couple times to make the pump run extra prime cycles.
Aug 1, 2018 at 8:04 PM
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ROBERT CURTISS
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But the slow start is not the primary issue, it is the rough running and rich engine condition. So the check valve on the pump might be faulty, but not in the way I need to repair.
Aug 1, 2018 at 8:12 PM
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PATENTED_REPAIR_PRO
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I was not talking about the return line, but the high pressure line.
Aug 1, 2018 at 9:20 PM
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STEVE W.
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Cannot be plugged. You would only get a higher than normal pressure in front of the regulator if something downstream of it was blocked to dead head the pump and stopping fuel flow. If it was plugged before the injectors the pressure at the injectors would be lower, not higher.

Robert -
The bleed down will not be a problem at the moment, just once you get things repaired and it is running correctly.
The higher pressure could cause the rich condition, but with old fuel with a lot of the volatile compounds gone it will not run very good either. That is why I would get good fuel into it. You might be repairing a problem that is being caused partially by the bad gas.
Was it running good when parked?
Aug 1, 2018 at 10:45 PM
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ROBERT CURTISS
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As far as can be recalled, it was running well when parked. There is not much gas in the tank, basically on 'E'. I do not want to spend the time to drop the tank and am thinking of just getting enough new gas in there to dilute any bad gas in the tank. I know, not the best option, but certainly the simplest. I will get some gas in the tank and recheck the fuel pressure with a new gauge.
Aug 2, 2018 at 7:30 AM
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PATENTED_REPAIR_PRO
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When you squeeze the end of a garden hose to produce back pressure the water coming out is under more pressure. That is why it shoots so far out from the water nozzle.
I feel as though I am arguing with another expert on here, how is this helping a customer?
I will stop putting in my two cents worth so at least the customer does not get confused.
Aug 2, 2018 at 8:50 AM
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ROBERT CURTISS
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Okay, I got hold of a different fuel pressure gauge, no changes. I replaced the fuel filter (and now smell like gas, sigh) while the filter was off, I attached a tube and cycled the fuel pump and removed all the gas from the tank. I poured in a few gallons of newer gas I had on had.

It is still at 70 then 60.The bleed seems much slower, even though there was no fuel leak at the filter (before nor after). It seemed to idle better with the newer gas, but still not right.

After a few minutes, the 'service engine soon' light started to blink. I did not get the truck up to running temperature, but at least enough to get the temperature needle to move.

It is still running at 66 psi Faint white smoke out the tailpipe, ticking noise that I tried to capture on video.

When I replaced the fuel pump, I know I had issues hooking up one of the vent hoses to tank that are not near the fuel pump assembly. I also know that I had issues with getting the busted fittings out of the fuel hoses and had them twisted a bit but they seemed fine on installation. I am hoping not to drop the tank again as it is a pain as a single man job.

Thoughts? I am heading out of town tomorrow until Wednesday so I will not be able to do much more today. I appreciate both of your insights in trying to solve this problem for me.
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Aug 2, 2018 at 11:09 AM
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STEVE W.
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Blinking CEL is likely a misfire. After setting that long it could be one or more stuck poppets on the injectors, or you could have a valve or two not closing fully.
Being a 1995 this is one of the "fun" vehicles to pull codes on. It was the transition year. GM used a mixed mess on them that is called OBD 1.5 by many. It uses a blend of OBD I coding running on OBD II hardware. The paperclip trick does not work and most of the OBD II code readers won't read them either. There are a couple of the older Actron units that will read them. They are the ones that can read OBD I system but have the OBD II cable.

Some people have been able to get the system to flash the codes by jumping pins 5 and 6 in the DLC but I have never tried it.

Would not worry about the white smoke until you can get it to run and burn off all the moisture in the exhaust system.

We will be here when you get back to it.
Aug 2, 2018 at 4:33 PM
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ROBERT CURTISS
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Was the ticking noise any help? I am thinking of pulling the trigger on a whole spider unit once I get back. It seems to be such a high fail item from all the forums I have read through. Also, seems like 66 psi is not that much above the specification. I have seen 56-64 psi.

Off to Disneyworld, will not be an issue until I get back!
Aug 2, 2018 at 10:19 PM
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STEVE W.
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If you are thinking replacement, look at the conversion to the actual multi-port set-up that was used in later years, it is much better than the OEM CPI unit.
I listened to the tick. Could be related to the misfire but it is hard to tell. Once you get back you can use a stethoscope to listen to the engine and figure out what it is. Disable each cylinder one by one and see if it changes. Then work from there. I would not put a ton of money in it until it runs better.

Go enjoy the land of Mouse. We will be here when you come back.
Aug 2, 2018 at 11:06 PM
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ROBERT CURTISS
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Okay, I have good news and bad news. First, Disney was great, but that is a given.

I ordered and installed a refurbished spider unit. I did not replace the 'nut kit' that includes the two hoses from outside the manifold to the spider unit itself.

Results: Fuel pressure is now about 54 running, maxs at 60 when the pump is primed. The bleed down is super slow, maybe 1-2 psi per minute. Remarkably slower than before.

Bad news: Still have a ticking noise that seems to be coming from the middle of the engine below the level of the manifold. It is still flashing the 'service engine soon' light after about one minute of running, meaning a rich condition, as far as I know.

Where do I go from here? It seems that the fuel issues have been resolved. (Fuel pump, filter and spider assembly). The electrical system seems good with replacement of plugs, cap, rotor. All plug wires seem to be in great shape. Recently replaced before storage.

Aug 14, 2018 at 11:58 AM
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STEVE W.
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Flashing CEL means a misfire that is causing a problem. The ticking sounds like a rod bearing but it is hard to say for sure. I would start on one side and pull one plug wire at a time and listen for the sound to change. That will be the problem cylinder. Then do a compression and leak down test. It is possible it is a bad rocker or valve spring.
Aug 14, 2018 at 5:34 PM
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ROBERT CURTISS
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The ticking is the secondary issue. Rich condition (misfire) and rough idle with delayed rpm increases is the main issue. Maybe a bad MAP sensor?
Aug 14, 2018 at 5:59 PM
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STEVE W.
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I would try to determine what the ticking is first. Not really worth it to repair the rest and discover you have a bad crankshaft or bad rod bearing or that the engine has a bad valve. The misfire and poor running could easily be caused by a bad intake valve.
Aug 14, 2018 at 6:18 PM
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ROBERT CURTISS
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The ticking sound definitely comes from higher up on the engine where it is more likely a lifter or rocker versus lower in the engine where would be a rod. That being the case, is there a potential solution to the lifter knock? My goal is to get this vehicle sellable as soon as possible.
Aug 15, 2018 at 6:03 AM
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STEVE W.
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That would depend on if it is the rocker, lifter or a broken valve spring. Would not hurt to pull the valve cover and look. If it is on top it is an easy repair. If it is a lifter it should not be hard to replace a bad one as it has roller lifters.
Aug 15, 2018 at 7:13 AM
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ROBERT CURTISS
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Update!

I got out my auto stethoscope and the tick seemed to come from the top end of the engine (lifter/valve, not rod). I hooked up a timing light and the flashes seemed in the same cadence as the tick (lifter/valve, not rod) with the engine running I pulled each plug independently, not change in the tick (lifter/valve, not rod). So that is all good, right?

I added some motor flush to the engine and let it idle for five minutes according to the directions. I then completed an oil change, with filter. Ticking still present.

If this is just a lifter tick, I would like to ignore it for now, assuming it will not cause much more wear in the meantime while solving the other issue.

The engine light still blinks after a short time started (fifteen to thirty seconds) it does not stay solid while the engine is running nor when I shut off the engine then restart it.

The computer is an OBD 1. I only have a basic OBD II Bluetooth scan tool, so that is no help.

Where do I go from here? Replacing parts and hoping will get expensive quickly.
Aug 17, 2018 at 9:48 AM
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ROBERT CURTISS
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I tried to pull codes but have been unable to do so using the pin jump method. I only have wires on the OBD in 2, 4, 5, 9, 13, 16. I looked at videos and forums online and have not found a way to jump this vehicle to read any codes. For instance, one video shows jumping 2 and 6 (but I do not have a 6), another says 3 and 4 (but I do not have a 3). You see the issue.
Aug 17, 2018 at 10:15 AM
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STEVE W.
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You have OBD 1.5 in that. It is OBDII hardware that runs some OBDI software and some OBDII software. Jumping pins will not work. You need the proper scan tool. The old Snap-On brick and OTC Genisys will work as long as you have the proper cable and keys.
The blinking check engine is a misfire. It will not switch to a steady light as long as it is misfiring. You could use a spark tester and check each cylinder for spark. If it is a bad lifter it could cause a misfire through not opening one of the valves, on intake you would get a smaller or no charge into the cylinder. If exhaust it could keep all of the exhaust from exiting and that contaminates the incoming fuel charge.
Aug 17, 2018 at 4:02 PM
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ROBERT CURTISS
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I have not been able to get to the truck in a few days. I tested for spark using my inductive timing light as near to the spark plugs, all wires had spark. The other night I went out and started the truck and looking for arcing. I did not see any around the plug wires, plugs nor the coil.

Getting to the lifters is definitely opening up more of the engine than I want to. Any other thoughts before I am left to that and hoping there are some bad ones in there?
Aug 20, 2018 at 12:51 PM
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STEVE W.
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Well, you mentioned you wanted to sell it so maybe sell it as is?
The other option is to go in and see what the tick is. You should be able to tell if it is lifters with just the valve cover off.
Aug 20, 2018 at 1:02 PM
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ROBERT CURTISS
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Remove the valve cover and look for movement? Or lack thereof?
Aug 20, 2018 at 1:11 PM
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ROBERT CURTISS
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At this point, I do not want to admit defeat and sell it as is.
Aug 20, 2018 at 2:02 PM
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STEVE W.
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Pull the valve cover and look for loose rocker arms or bent push rods. That would tell you if there is a problem.
Aug 20, 2018 at 4:50 PM
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ROBERT CURTISS
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I pulled one cover off today (I did not have time to get to the other). Nothing apparently wrong. Only two rockers had minimal 'wiggle' but I am sure that is just them being on the low part of the cam lobe. Push rods looked good for what I could see. I could not depress any of the push rods from where they were.

I will open up the other side tomorrow.
Aug 20, 2018 at 4:57 PM
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ROBERT CURTISS
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I think I found a problem, lol.

So, do I just get another pushrod and hope it was a fluke or open it all the way to inspect further?

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Aug 21, 2018 at 9:23 AM
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STEVE W.
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Not pretty. I would get a cheap bore scope and look into the lifter valley to see what the lifters look like. They could be okay but is sort of doubt it. My suspicion is that the lifter came apart, the push rod dropped and got caught and turned into a pretzel. The question is, where did the lifter fail? If it is on the top side a new one would do the job. If it failed at the roller end then you would likely need a new cam as well because the lifter may have gouged the cam lobe.
Aug 21, 2018 at 3:08 PM
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ROBERT CURTISS
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I ordered a scope from my phone, it will be in Thursday. I really do not want to open it up.
Aug 21, 2018 at 5:01 PM
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ROBERT CURTISS
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So I looked and saw the following photos, not sure what I would expect to find if it was bad. Obviously the lifter guide has some damage, but otherwise looks good. Thoughts?
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Aug 23, 2018 at 10:40 AM
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ROBERT CURTISS
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Great news, I went to a 'you pull'em' salvage yard and they did not even have me pay for the three push rods I took. (I only needed one, but why not have a spare or two?)

I installed in and was able to get everything put back together. Fired right up and runs great. I mild hesitation, but nothing I am concerning myself with at this time. I let it idle for about twenty minutes, then drove up to the gas station. All good!

Thank you so much for your time and insights into this matter. It was greatly appreciated!
Aug 23, 2018 at 2:54 PM
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STEVE W.
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So no tick just the hesitation? Great to hear. Probably could use a good "drive it like you stole it" run to clean it out.
Aug 23, 2018 at 3:31 PM
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ROBERT CURTISS
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And the hesitation is pretty minor. I am sure it will do better with more running. Time to get it sold before any new problems come up!
Aug 23, 2018 at 3:43 PM
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STEVE W.
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That would be a good idea. The lifters looked okay, would be interesting to know exactly what occurred to pop that push rod out. I have seen the rockers fail on them. I suspect it was a case of a lifter sticking. May want to change the oil and filter. Then slap the for sale sign on it. Good luck with the sale.
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Aug 26, 2018 at 8:59 AM
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ROBERT CURTISS
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I did change oil after a five minute 'motor flush' was added. Sold it yesterday! I am not sure what the cause was either but I think you are on the right track. The rocker seemed fine.

Thanks for all your assistance in what turned out to be a pile of issues instead of just one!
Aug 26, 2018 at 12:40 PM