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91 S10 TBI 2.5L problems

01-07-2006, 10:06 PM
After running for roughly 20 minutes it runs like shit. Acts flooded. New O2 sensor and Coolant Temp sensor. Pretty sure its not the ECM. New plugs etc as well, new fuel pump. Today when I was working on it my oil pressure gauge started acting wacky too, whenever I would give it some solid throttle it would go all the way up to 80. Any ideas?

01-07-2006, 10:09 PM
Forgot to mention, no service engine light. EGR valve is functioning properly as far as I can tell. 160k miles.

01-08-2006, 02:58 PM
Anyone??? I am going to get new plug wires tommorow and see what happens.

01-08-2006, 03:07 PM
Make sure both injectors are spraying also check for excess fuel pressure if the injectors check out.

01-08-2006, 08:08 PM
I've got the 2.5L as specified, therefore only one injector. I know its spraying, it runs rich as hell when it gets to doing this.

01-09-2006, 07:22 PM
New plug wires, no fix.

01-10-2006, 05:50 PM

01-10-2006, 07:15 PM
check timming? vacuum leaks?

01-10-2006, 07:17 PM
No leaks and I do not see how timing would be a problem since it takes 15-20min before it acts up.

01-11-2006, 10:34 AM
ok, well good luck.

01-11-2006, 10:40 AM
i need some help. i want to kno how to hook up a 4 channel amp up. 800w competetion. is there a certain way u have to hook them up

01-11-2006, 02:35 PM
Start your own thread jackass. (talking about numberal)

dmbrisket 51
01-11-2006, 06:00 PM
maby the injector is overfueling, get a hold of a dmm and find out the resistence, look up what resistence should be, does it get up to temp by this 20 min marker? rich means it is not a vaccume leak, but a lack of air to fuel ratio... does this happen under a load or at an idel? both? if you want to make sure it is an over fueling problem, disconnect the break booster to cause a massive vaccume leak, if it needs more air, this will help it run better

01-11-2006, 10:39 PM
A couple of people told me to take out the Ignition Control Module and take it to AutoZone since they test it for free, thing that could be a worthy cause?
Also, yes, the temp gets up by this time and it happens regardless of if it is at idle speed or running speed. Whereabouts can I find the break booster? Or should I be able to find it in my Haynes manual?

dmbrisket 51
01-11-2006, 10:46 PM
slight possibility, ignition coil not hot enough, or arcing out, not a good spark, wont burn all the gas... get it checked at az, but dont buy from them, get a delco replacment, will last the longest, and work the best... the break booster is that big black thing on the drivers side on the fire wall, its a big disk with a vaccume hose going to it from the manifold... and the oil pressure is a sender going bad, dont worrie about it, all chevys do it after 50k

01-11-2006, 10:54 PM
Well with the arcing out we ran it on a cloudy pitch black night and saw absolutely no evidence of anything like that. I don't know about the injector itself being the problem though I do suppose it is a definate possibility, as we took it out and looked at it and ran some cleaner through it. So I am assuming to test it I just need to attach to the terminals within the plug on the injector and test as mentioned?

dmbrisket 51
01-11-2006, 11:01 PM
remove the injector plug, and put one lead on one side of the injector and the other lead on the other

01-12-2006, 06:37 AM
Thats what I meant. :) I will give this stuff a try this afternoon after work and post back with the results.

01-13-2006, 03:05 PM
Can't seem to get the distributor cap off, what kind of screws are on it?

01-13-2006, 07:00 PM
have you not changed out cap and rotor yet? 2 philip head clamps. one on each side, put screwdriver on and push down and turn counterclockways. once you turn enough the head will pop up(spring loaded). have you changed plugs?

01-13-2006, 11:12 PM
New O2 sensor and Coolant Temp sensor. Pretty sure its not the ECM. New plugs etc as well, new fuel pump.

I intend on taking out the Ignition Control Module and getting it tested, as I've been told by a couple of people now that is a possible issue.

01-13-2006, 11:56 PM
but i dont understand why put so much time and money into it and end up with just doing a half ass tune up. most would of atleast looked inside the cap to make sure good clean contacts between rotor and cap. this will cause weak to no spark and very sluggish proformance.
in ypur first post you said you replaced plugs and etc. what do you consider etc? i recon cap and rotor isnt one of them, huh? lol!!

01-14-2006, 10:21 AM
Well I haven't put much time and money into it yet. Half-ass tune up? Well ya see, it ran fine for a good while after I bought it and I just do not see why that would be the problem since it takes it so long to do it. And I do believe I asked about the cap etc because I have never done it. Sorry I am not "most of you". I appreciate your advice but tone it down a tad please.
I've got good spark. Like I said I am going to pull the ICM out of the Cap and take it to the Zone and see how that goes.

01-14-2006, 07:15 PM
sorry didnt mean to come off all hard. alot of problems are solved by a simple and complete tune up.

01-14-2006, 09:16 PM
No problem, I realize that a tune-up may fix the problem so what I have been replacing follows the lines of a tune-up, I just can't afford to do it all at once.

01-27-2006, 07:24 PM
Have you checked the fuel pressure regulator, its behind 4 torx screws just to the left of the injector, typically when running very rich that is the culprit. and there cheap too.

01-30-2006, 02:46 PM
I checked it and it appears to be fine.

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