hard to start

Check the fuel pressure and test the coolant temperature sensor, also scan the computer for OBD2 code/s then comeback.

This guide can help us fix it

https://www.2carpros.com/articles/engine-cranks-excessively-before-starting

Please run down this guide and report back.

Sometimes my engine bucks back when starting hot or cold. No fluid leaks are aparent and gas milage is good. Performance has not been afected.

Start by checking the cold start valve. This valve (actually an injector in the intake) adds additional fuel to engine during cranking. If malfunctioning it can cause long starts, or bucking.

Start by disconnecting the connector, if you notice any change, then use a noid light to see if it is getting power during cranking (it is only active during cranking).

Also check fuel pressure regulator for the presence of gas in vacuum line.

If problem persists, check fuel pressure with a mechanical gauge. With gauge attached to test port, turn ign. to ON and fuel pressure should go up to 40-45psi and hold that pressure for a couple minutes, if it goes down quickly, then FPR or a leaking injector.

97 s10 engine starts hard ( a lot of cranking) after engine temp has been reached, also notice hard starting when the ac is on?

Do a fuel pressure check make sure its within specs and test the fuel pump relay come back with some results.

I have 63lbs when the key is turned on and about 55lbs while it is running. should it retain any pressure after the pump cycles when the key is turned on?

Sometimes it starts fine and sometimes it cranks for a while. Put on a new fuel filter last week.

does it matter the temperature of the engine, temperature of the air outside, moisture in air, time of day?

Cold engine, 45 degrees, dry at 5:00 a.m.

and it doesn't always do it under those conditions?

does it get better when its say 50-60 degrees, or worse when its 0-30 degrees?

Here's my problem. The engine cranks for about 5 seconds, then either dies or starts very rough and stalls. Immediately after, when cranking for a second time, the engine starts perfectly after 1-2 seconds with a good idle. Could the Oil Pressure switch that cuts power to the fuel pump when the pressure is too low be the culprit? If I keep cranking to get the pressure up, it stalls, and then immediately after crank again and the pressure is high enough, it'll start... It ALWAYS starts on the second start. Is there a bypass to the sensor when the starter is engaged?

More likely you have a blown fuel pressure regulator that is dumping raw fuel into the engine causing the misfire and the lack of fuel pressure on initial start up.If you remove the upper intake (plastic cover) the reg is on the pass side, if it is gas washed under it, the reg is bad.

Well, the truck is only getting about 10 mpg as it is, might that also point to a blown fuel pressure reg.? By the way, the engine is brand new (reman) with only 2500 miles on it. The intake manifold is new, also.

Thanks,
Nick

That again points to the regulator being blown.I would check it out so you dont wind up gas-washing the cylinders and hurting your new engine

I do have a fuel pressure tester, are there any tests I could run before I go in and take the intake manifold off?

Thanks

If the fuel pressure doesnt jump up when the engine is reved,the reg is bad.

It jumps up to about 65-68 psi from an idle psi of about 57... The pressure is also stable when the engine is turned off, no drops, etc.

The engine revs perfectly even up to Redline without a miss or anything...

could be an injector bleeding down over time. Leave the gauge on it to see what hapens to the pressure. Might even be a bad oring in the fuel/injector block in the intake

After shutting the engine off with a fuel pressure reading of about 61 PSI, 5 to 10 minutes later, the pressure is down to about 45 PSI.

Does this signal a leaky injector? What's my next step?

Thanks,
Nick

Still might be a leaky regulator.I have actually pulled out the injector nozzles and rested them on dry rags to see if any of them were leaking down.

After about 10 hours of sitting cold, I checked the pressure and it's reading 0 PSI...

That is why it is hard starting, no fuel pressure, it has to build it back up and the lines have air in them before it can start

I have some more information that might be of some more assistance...

I noticed that the engine will have a severe misfire (strong enough to flash the MIL and set the P0300 code), but only in 2nd gear. If I'm going 35 miles an hour in 2nd gear (about 2500RPM) and I try to coast or maintain a certain RPM above 2000 and lightly have the accelerator pressed, the misfires happen... When I accelerate in 2nd, nothing. This problem doesn't happen in Over Drive. When I stop in 2nd, nothing...

The engine was also at operating temperature, but it will also do it when it's cold.

The first time I tried to recreate the conditions and set the P0300 code, it also set P0147 and P1351 along with it. The second which I let it misfire only for a short period of time, set only the P0300...

P0147- o2 heater circuit
P1351 - ignition control circuit high voltage
Both of these could be related to a faulty PCM or bad wiring/connections. Test to see if you have 12 volts at the o2 sensor for the heater circuit. If so, the sensor may be bad, but the other code requires alot more diagnostic. Have you signed up for our online manual (Mitchell) to use as a diagnostic aid?

No, I have AllData...

I have a question though... The engine that came in my truck was an X-Vin 4.3L V6. When that engine threw a rod, it was replaced with a long-block W-Vin 4.3L V6 engine. The PCM is original from the X-Vin. Are the PCMs the same from VIN to VIN?

Nick

The original was an X or Z? Z is throttle body. The PCM wont matter, you didnt change the fuel injection, only the engine under it

The original was an X-Vin engine.

I did notice today that the misfire also occurs much more frequently when the truck is cold... Even in park, the engine would misfire repeatedly when revved and even when under full throttle. This disappears when the truck warms up...

Nick

Starter will not engage at all times and when key is turned solenoid clicks. If you hold in the clutch still clicks. If you pump the clucth and continue to turn the ignition switch eventually it will fire over. I dont believe the starter is bad because it does start. could the clutch switch be the problem?

Is the click coming from the starter? If so, chances are the solenoid is bad on the starter and needs replaced.

Let me know. Also, if you still feel the starter is fine, try this. When it won't start, have a helper turn the key to the start position while you check for voltage to the smaller wire on the starter. You should be getting 12+ volts. I you are, replace the starter. If not, let me know.

Actually after pulling the starter I found the issue, Turned out to be the main posative wire from battery to starter was bad. Reolaced the wire and starts fine now. Thanks for your assistance.

I'm glad you found the probem. A bad cable will do it. Let us know if you have questions in the future.

Joe

Engine problem
1996 Chevy S-10 6 cyl Two Wheel Drive Automatic 140K miles
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I have a 1996 Chevy S-10 with 140,000 miles on it. It has a 4.3 V-6 Vortex. I'm having a hard time starting it cold or hot, but it runs perfect once it starts. I've done a major tune up, including spark plug wires, distributor cap, rotor, fuel filter, air filter, fuel regulator valve, throttle body, oxygen sensor 1 & 2 and a new fuel pump and it's still starting hard. Any suggestions as to what I can try next?
Thanks a lot,
Lou

check your fuel pump relay. your fuel pump relay is what gives your fuel pump juice for 2 seconds prior to engine starting to prime the fuel system. check this then get back to us. we can definately point you in the right direction.

I have a 1996 S10 pick--up 2.2 engine. When it's cold I have to crank it about 10 seconds to get it to fire. Sometimes longer. I have already replaced the fuel pump and filter. When it's warm, it is better but not like it should be.

When I changed the fuel pump, the tank was rusted quite a bit where the fuel pump flange seals and it leaks when it is overfilled. Could this be the problem?The truck started fine for quite a while after changing the pump. Just this summer, it has started starting hard. It was a gradual problem. It wasn't an over-night problem.

If you have a leak at the pump gasket, your ses light should be on and a code for a minor, and gross leak should be stored, if so, you know the answer...replace the tank, this is step one!

Engine Mechanical problem
1996 Chevy S-10 4 cyl 100000 miles

Hard to start, but when started, runs OK. Have to use starting fluid

Welcome to the forum. How long since a tune-up? Use a gage and check fuel pressure. If you have the spider fuel system, they are known for a hard cold start. The fuel poppets may need to be cleaned. The best cleaning procedure is a shop procedure.

The car almost always needs two tries to start. once started, acceleration is sluggish for about a minute. once it's warm it, runs fine. i had it tuned up about a year ago and just had the fuel injectors replaced. fuel pump?

[quote:1ab045d20f="s-10guy"]Engine Performance problem
1999 Chevy S-10 6 cyl Four Wheel Drive Automatic 160000 miles
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The car almost always needs two tries to start. once started, acceleration is sluggish for about a minute. once it's warm it, runs fine. i had it tuned up about a year ago and just had the fuel injectors replaced. fuel pump?[/quote:1ab045d20f]

if it runs fine warm its not the pump, do you have a ck engine light on? you can go and get a free scan at autozone, if you dont have a light on tell them it comes on and off, that way you get history codes

I have a 1996 S-10 w/127,000 miles. Vortec V-6. It has been a great vehicle, but in the last few weeks it has been starting hard when the engine is hot.
When the engine is cold it starts with just a half crank of the starter. However once it gets warm or hot, it cranks for 5 or 6 seconds and then starts like it was flooded. There are no codes. Is this a problem with the TBFI or with a sensor. I need this vehicle for everyday use and am afraid that it will shut off on me if I don't get it fixed. Thanks for any help you can provide. :P