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Old 10-24-2016, 06:45 PM   #1
rcweston
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s10 2.5l very very hard to start in mornings (now corrected)

This 88 s10 with a 2.5l engine has worked wonderfully for a long time now. 2 months ago I parked it and the next day couldn't turn it over. It tried but the pistons wouldn't move. Removed spark plug #3 and it was full of water. Changed the head gasket, the valve cover gas, the manifold gaskets. Put it all together and it runs like a champ.. about 3 weeks later it is hard to start. Very hard. It turns over OK but doesn't fire. After 20-30 short tries to start, it finally hits a couple of times. Within 10 more tries, it starts to hit more often, then finally starts. Once started, you need to keep it revved a little or it will die. After about 1/2 mile of driving, all is well, it runs great from then on. After shutting it off, it will start right back up, unless it sits for a long period of time,3-4 hours, then it has problems again.
I had what seemed to be the very same problem about 3 or 4 year ago. I was getting water dripping on the distributor from the intake manifold water jacket exit port. It would cause the distributor to send the spark to ground instead of to the spark plug. after a lot of trying, it would also start then.
This is not the problem this time. the distributor and spark plug wires and plugs checks out very good. The oil is great, no water in it.
Could this be something as simple as the fuel filter? I have never really worked on the fuel end of a car, but I suspect that the pump keeps pressure on the fuel line and the injectors release it into the intake port or carburetor. I have no idea what the pressure should be, but I did not find a valve that will release it if pushed.
Could anyone give me a layman's explanation of how it all works? Does excess fuel return to the tank?
or if you have any other clues of what is gong on here, I'm open to any suggestions.
Thanks Rex

Last edited by rcweston; 03-08-2018 at 12:08 AM. Reason: correction
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Old 10-26-2016, 08:47 AM   #2
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Very very hard to start in the mornings

I posted this in the s10 forum, but didn't get any responses, maybe some one here has a thought or info.

This 88 s10 with a 2.5l engine has worked wonderfully for a long time now. 2 months ago I parked it and the next day couldn't turn it over. It tried but the pistons wouldn't move. Removed spark plug #3 and it was full of water. Changed the head gasket, the valve cover gas, the manifold gaskets. Put it all together and it runs like a champ.. about 3 weeks later it is hard to start. Very hard. It turns over OK but doesn't fire. After 20-30 short tries to start, it finally hits a couple of times. Within 10 more tries, it starts to hit more often, then finally starts. Once started, you need to keep it revved a little or it will die. After about 1/2 mile of driving, all is well, it runs great from then on. After shutting it off, it will start right back up, unless it sits for a long period of time,3-4 hours, then it has problems again.
I had what seemed to be the very same problem about 3 or 4 year ago. I was getting water dripping on the distributor from the intake manifold water jacket exit port. It would cause the distributor to send the spark to ground instead of to the spark plug. after a lot of trying, it would also start then.
This is not the problem this time. the distributor and spark plug wires and plugs checks out very good. The oil is great, no water in it.
Could this be something as simple as the fuel filter? I have never really worked on the fuel end of a car, but I suspect that the pump keeps pressure on the fuel line and the injectors release it into the intake port or carburetor. I have no idea what the pressure should be, but I did not find a valve that will release it if pushed.
Could anyone give me a layman's explanation of how it all works? Does excess fuel return to the tank? what amount of pressure are we looking for?
or if you have any other clues of what is gong on here, I'm open to any suggestions.
Thanks Rex

Last edited by rcweston; 03-07-2018 at 11:48 PM. Reason: correction
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Old 10-26-2016, 08:53 AM   #3
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Re: Very very hard to start in the mornings

Yesterday, I took off the air filter and cover to watch as my wife started the truck. My goal was to see if fuel was entering the carburetor. It was, and the truck started up without any hesitations, just as it always has in the past. did not have a problem.
This morning, it was hard again so I put a little gas in the carb, it started quite a bit better but still had some problems keeping going for about 15 seconds, then it was fine.
Any suggestions?
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Old 10-26-2016, 08:54 AM   #4
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Re: s10 2.5l very very hard to start in mornings

Yesterday, I took off the air filter and cover to watch as my wife started the truck. My goal was to see if fuel was entering the carburetor. It was, and the truck started up without any hesitations, just as it always has in the past. did not have a problem.
This morning, it was hard again so I put a little gas in the carb, it started quite a bit better but still had some problems keeping going for about 15 seconds, then it was fine.
Any suggestions?
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Old 10-26-2016, 04:15 PM   #5
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Re: s10 2.5l very very hard to start in mornings

Gas in the carb?, is this a TBI, or carb engine.
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Old 10-26-2016, 08:28 PM   #6
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Re: Very very hard to start in the mornings

Are we certain it is a carburetor? Most of the 151s used a TBI system by 1988. If it is the TBI system, verifying that the fuel pump is delivering 11-13 PSI would be a good step.
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Old 10-26-2016, 08:30 PM   #7
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Re: s10 2.5l very very hard to start in mornings

I just noticed that we have TWO threads running on this topic. They are being merged now.
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Old 10-27-2016, 10:26 PM   #8
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Re: s10 2.5l very very hard to start in mornings

Quote:
Originally Posted by maxwedge View Post
Gas in the carb?, is this a TBI, or carb engine.
Your correct, this isn't a carburetor, it has throttle body injection. after it was started, I can see the gas being released onto the closed butterfly valve in the throttle body. Sorry for the confusion.
I added a bottle of chevron techtron cleaner. It starts easier these last few days, but not as good as it did a month or so ago. It still takes 4-5 starting tries to get it going.
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Old 10-27-2016, 10:31 PM   #9
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Re: Very very hard to start in the mornings

Quote:
Originally Posted by Blue Bowtie View Post
Are we certain it is a carburetor? Most of the 151s used a TBI system by 1988. If it is the TBI system, verifying that the fuel pump is delivering 11-13 PSI would be a good step.
Thanks for replying. From your reply, I take it that there should be 11-13 psi on the fuel supply line. I'll see if one of the parts store has a gauge I can test it with.
On my other vehicles, I can here the gas pump start as the key is turned on before the key is turned to the start position. I don't here that with this truck.
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Old 11-04-2016, 08:31 PM   #10
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Re: Very very hard to start in the mornings

Quote:
Originally Posted by Blue Bowtie View Post
Are we certain it is a carburetor? Most of the 151s used a TBI system by 1988. If it is the TBI system, verifying that the fuel pump is delivering 11-13 PSI would be a good step.
After adding the techron cleaner to the gas tank, the problem started to be less and less. After a week, it has completely gone away. The truck starts first try just as it always has. So now the big question, what caused the problem? could it have been something that got cleaned up with the Techron? or could it be that the trouble was going away on it's own, and the use of the Techtron just happened to be at the same time?
I'll probably not be able to answer that question, but if someone out there that is familiar with these type of scenarios has any info that might help to correct it before it happens again, Please add to this thread.
Thanks everyone for your help
Rex
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Old 03-08-2018, 12:03 AM   #11
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Re: s10 2.5l very very hard to start in mornings

just got back after being out of state since 2016. here's a solution to the problem.
the trouble came back fall of 2016. changing the fuel filter seemed to correct it, but it was only a band aid. It shortly became almost impossible to start, but I was gone and soninlaw driving it just stopped driving it.
in Jan2018 started testing all over again. found bad air motor that lets hot air into air stream to help with throttle injection. Replaced it. tested pvc, egr, map temp sensor (both) throttle position sensor, oxygen sensor. and every thing else I could find except for the fuel pressure because it has no access port and steel lines that are almost impossible to get to.But I did test the relay, fuses and gas pump, all were operating. done restive checks on fuel pump wires and tested fuel regulator. everything I could except fuel pressure. After all I could see fuel being injected at the throttle body!
finally I found a port adapter that would fit inline under the truck. It was in a kit $150 at auto zone. they loaned the kit out. finally I see that the pressure was very low, around 3 psi.
Took off the bed and removed the pump, replaced it and retested everything. this was the problem all along.
the truck runs better than it has for years even though it ran well before. the engine doesn't idle high at stop signs any longer.
I found a pump that reached only 18 psi. on line and it works perfectly.
I could have saved a lot of frustration if I could have tested the pressure sooner, but their are no access ports on this tbi system and the lines are so difficult to even add the port adapter.
thanks everyone for you help with this ongoing problem.
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Old 03-10-2018, 08:18 AM   #12
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Re: s10 2.5l very very hard to start in mornings

Good update information. After having experienced this myself, I suggested the pressure test . That's not easy on early TBIs as you discovered, but necessary. Your 18 PSI pump should work fine if the FPR unit at the TBI is functioning properly.
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