Fuel regulator

Welcome back, JC

The regulator on your truck is vacuum operated. To check it, you need to do a fuel pressure test and basically disconnect the regulator to see if things change. I will tell you that often times when they fail, it will draw fuel into the vacuum hose, so pay attention when you remove it.

Here is a link that shows in general how to check pressure and the regulator:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Here are the directions specific to your vehicle for checking pressure and the regulator:

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FUEL PRESSURE CHECK
PROCEDURE

(pic 1)

a. When reconnecting fuel line, always use new clamps.
b. Make sure that clamp screw does not contact adjacent parts.
c. Use a torque driver to tighten clamps.
d. Use Pressure Gauge to check fuel pressure.
1. Release fuel pressure to zero.
2. Disconnect fuel hose between fuel filter and fuel tube (engine side).


(pic 2)

3. Install pressure gauge between fuel filter and fuel tube.
4. Start engine and check for fuel leakage.


(pic 3)

5. Read the indication of fuel pressure gauge.

At idling: Approximately 235 kPa (2.4 kg/sq. cm, 34 psi)

A few seconds after ignition switch is turned OFF to ON:
Approximately 294 kPa (3.0 kg/sq. cm, 43 psi)

6. Stop engine and disconnect fuel pressure regulator vacuum hose from intake manifold.


(pic 4)

7. Plug intake manifold with a rubber cap.
8. Connect variable vacuum source to fuel pressure regulator.
9. Start engine and read indication of fuel pressure gauge as vacuum is changed.
Fuel pressure should decrease as vacuum increases. If results are unsatisfactory, replace fuel pressure regulator.

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If you find the regulator is good and the injector needs replaced, here are the directions. The remaining pictures correlate with these directions.

INJECTOR REMOVAL AND INSTALLATION
PROCEDURE
1. Release fuel pressure to zero.
2. Remove injector tube assembly with injectors from intake manifold.


(pic 5)

3. Remove injectors from injector tube assembly.
- Push injector tail piece.
- Do not pull on the connector.


(pic 6)

4. Install injector to fuel tube assembly.
a. Clean exterior of injector tail piece.
b. Use new O-rings.
Always replace O-rings with new ones.
Lubricate O-rings with a smear of engine oil.
5. Install injectors with fuel tube assembly to intake manifold.
Tighten in numerical order shown in the figure.
a. First, tighten all bolts to 9.3 to 10.8 N.m (0.95 to 1.1 kg-m, 6.9 to 8.0 ft-lb).
b. Then, tighten all bolts to 21 to 26 N.m (2.1 to 2.7 kg-m, 15 to 20 ft-lb).


(pic 7)

6. Install fuel hoses to fuel tube assembly.
7. Reinstall any parts removed in reverse order of removal.

CAUTION: After properly connecting injectors to fuel tube assembly, check connections for fuel leakage.

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If you replace the injector, check all rubber o-rings. You don't want a fuel leak. A small nick can cause a leak. Also, I always lube the o-rings with petroleum jelly. Sounds crazy, but it works great.

If the injector was dumping fuel, make sure to change the oil. I hope it didn't hurt the catalytic converter.


Let me know if this helps or if you have other questions.

Take care,
Joe

Thank you.
This is very detailed and informative. Exactly what I needed. The injector problem is all new to me. And Expensive as well number two.injector on the rail is stuck in open position and allowing gas to keep pouring into the cylinder. I tried cleaning it but still stuck. So I am replacing it as well as checking out the regulator. Thanks again you guys are great. I will make a donation when this is completed. Again thanks for the great information and diagrams. JC

I am happy to help. You have your hands full. Let me know if you need anything.

Take care,
Joe

Hello Joe,

After replacing the injector that was stuck open. I turned on the key and to my surprise the injector was fine but the one next to it started spraying fuel. It was not spraying before. What could be causing this? Possibly a wrong cap on the wrong injector? Or should I have replaced all injectors? The Hitachi injectors are very costly. Thanks. Joe

Welcome back:

Chances are you damaged the o-ring or it did not seat properly. I would take it apart and check. I would not replace all the injectors, but replacing the o-rings is cheap. Also, I always lubricate the o-rings with petroleum jelly before I put it together. That way it has less chance of damage.

I attached a picture of the injector and o-ring.

Let me know if this takes care of it. Keep in mind, the smallest nick in the o-ring can cause a leak because of the pressure they are exposed to. Additionally, make sure everything is tightened as per the prior post.

Joe

Hi Joe, I got a question it may sound stupid what I am going to ask but while working on getting the engine back into the truck and all the wires and hoses put back in their correct places I forgot to reattach the ground strap engine to frame/body. Would this make the injectors go nuts? To let you know what I am doing I am pulling the fuel rail out of the intake and turning the key to on position. This the spraying from the injector. Now after attached the battery ground. And engine ground. I turned on the key and much to my surprise no spraying injector is this crazy or am I on to something? When cranking the engine it idles great but at about 2,000 RPM holding the gas pedal steady the engine surges up and down like it has a fuel problem. So it is like were the injectors problem solved or not. And I smell raw gas. But no gas is coming out of the exhaust manifold like it was when the injector was stuck. So if you can figure this out I would sure like to hear your opinion. Thanks Joe. JC

Welcome back, JC:

Electric is really interesting. It will always find the easiest way out. Thus, if you remove the primary ground, it will try to find the next easy ground. As a result, all kinds of things happen. Lights can come on when they should not, gauges can function when they should not, and I am sure injectors can get power when they should not.

Now, you should not smell raw fuel. Any fuel leak is dangerous. Recheck the injectors to make sure the o-rings are not leaking. It is really easy to nick one when installing.

As far as the idle, it too can be related to ground issues.


I attached two pictures/schematics of the grounding locations. Electrical components are listed and their ground location is also indicated. Thought this would help.

Let me know if you have other questions. Make sure to locate where the raw fuel smell is coming from. Also, check the o-rings on the injectors for leaks. By the way, no question is stupid. This was a very logical question.

Take care,
Joe

Your great thank you so much so to update you I got the high idle fixed it was a crankcase ventilation hose running from the bottom of the intake to a little box that's bolted to the timing chain cover.replacing the hose brought down the idle.So now all I have to do is figure out why the engine is surging when hold the rpm at around 2000 .Surges bad when I shut it down that's when I smell the gas. Probably unburned coming out of the Exhaust because it's not leaking gas. Thanks again Joe. JC

It sounds like you are getting there. Take a look through this link as see if there is anything that helps.

https://www.2carpros.com/articles/engine-surges

Let me know.

Joe

Hello Joe, You may be on to something. It did not cross my mind to check the gas filter going to fuel rail. Though I do know it has gas flow after the filter because of the injectors issue I was having gas was coming through plenty. I personally think it is vacuum related. There is still one hose that has not been installed it got thrown away and possibly may make a difference. Though it is not a vacuum line I do not think it has vacuum. But not sure. It has a vent hose runs from bottom of intake to timing chain cover. A little metal box with one inch nipple. Needs replacement. But brand new plugs after running five minutes are black with soot this makes me think to much gas. This is why I am smelling gas when I shut it off. It is exhaust fumes. Joe please help me figure this one out. You been a big help it has come a long way since you guys started helping me. Great team you guys are. Thanks, JC

We need to figure out what hose is missing and what its purpose was.

I have attached a vacuum hose schematic for you to look at. Let me know if you can identify which hose is missing. Next, is a picture of a bad manifold absolute pressure sensor which is aprox where you said. See if that is what is missing the hose.

Okay, I will get on it tomorrow. I will try and send you some photos also. I put all vacuum hoses back where I thought they went to. The only one that has not been replaced is what I believe to be a crankcase vent hose intake to timing chain cover no hose. I will follow your photos and directions and let you know what happens. I am sure it is a hose. Thanks, JC

Hello Joe, I am checking the vacuum sensor the three hoses are connected. I do not think those were ever moved. But I noticed the ends of the hoses when I checked for cracks seemed to be a little wet with something.

I tried to send a picture but it did not send. I am sorry. JC

Joe, I worked on the truck today went over all the vacuum hoses sprayed a cleaner with engine running over all the vacuum hoses and there was no change in RPM at all. So rather than going in circles I am going to buy a OBD2 gadget and download an app called Torque. It is basically a scan tool and the app is free. I checked my diagnostics plug and it is a 16pin which is required for this tool to work. And maybe if I am lucky it will shed some light on this crazy problem. I checked the fuel filter fuels flowing fine. The truck runs perfect smooth no missing at all until you get past 2,000 rpm and then it just surges really bad. So if you happen to have a light bulb moment please let me know. But at this point I do not know what else to do. Thanks Joe for all your help. JC

Let me know what you find. I am interesting in knowing. I have have a feeling there is an issue with the camshaft position sensor, which is built into the distributor along with other components. However, without a code, I cannot be sure.

That's unbelievable I was thinking about buying a whole new dist.because it's in pretty bad shape. And I can get one cap and all for little over 50.00 it's driving me nuts. The head work was done by a machine shop valves seals etc.over 300.00 and the lifters are raising Cain ..very noisy.but I will for sure give you an explanation of what I find. One question while it's on my mind. When the head was installed was I supposed to use a sealer? If so I did not. Thanks talk to you soon. JC

Hi JC:
No sealer is used on a head gasket. I was taught long ago, if the surface is clean and dry, a gasket is all that is needed. Unless, however, it is recommended and it is on some components.

As far as the distributor, I would hate to be wrong. Please, Please. Please understand that is a theory. Without codes, it is nothing more than an educated guess. I will tell you the cam sensor does play a big role in injector and ignition timing.

I would not hold you accountable at all. My son told me to replace weeks ago. I just found one for $52.00 brand new rotor cap and distributor shipping included. So I am going go for it. If that is not the problem oh well another new part. It has got to be something simple because it idles beautifully it idles at about 800 rpm and great up to 2,000 rpm. I am almost positive all vacuum hoses are in their right places. So by next Friday the seventh I will let you know if the distributor fixed it. Please do not be concerned if not. It needs replacing anyway. I am thinking about a new oil pump too. I hate to swap original Nissan parts for aftermarket but the original parts gotta lot of miles. Okay, I will be in touch next week. Have a great weekend. JC

Sounds like a plan. Let me know the results.

Take care,

Joe

Thanks Joe, Happy Holidays.

Hi Joe, replaced my distributor and new injector still doing the surging. Will a loose bolt in the intake cause the surging?

Honestly, anytime air can enter the engine unmetered, it can cause a problem. One loose bolt is unlikely, but it is possible.

I am told to check the MAP sensor and catalytic converter. I will do that today. JC

I removed the exhaust pipe from the catalytic converter and it only made it worse. So I do not know what to do now. Ken suggested Map sensor. JC

Yep, I would try a MAP and MAF sensors one at a time because if they are off it may not set a code. Check out the diagrams (below). Please let us know what you find.

Cheers, Ken

Thanks Ken. I have someone coming over with diagnostic tool so he should be able to find the problem. JC

Please let us know. :)

I certainly will. Thanks JC