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Discussion Starter · #1 ·
When I go to school and start her up, everything is fine (7am) after school,(3pm) i start her up and she will not idle. i have to push the gas a little bit. this was normal and i lived with it for a month or three.

installed a new fuel sending unit. now, when its warm, it will not idle and, when driving at around 1500rpm, stumbles. This stumbling feels EXACTLY like im out of gas. (i have about 1/4 tank)

Wondering if this stumbling was just the idle problem getting worse? Could my occasional (lasting 5 seconds or so) CEL be related?

What weve done to fix idle: new exhaust inc cat, new 02, new thermo, sea foamed it once, new plugs, timing corrected, new wires. thats all i can think of. that was maybe may of this month.
 

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Vac lines, Fuel Pressure Regulator, nasty injectors, corroded wiring in the injector or ignition harness, failing alt causing fuel pump to cut out. Just a few thing off top o my noodle.

~psguardian
 

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That sounds like the tps is not working. Start there and move on to your coil and distributor they might be getting hot and shorting out internally.
Good luck Brad
 

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Discussion Starter · #4 ·
okay weve gone through and replaced most vac lines, rebuilt injectors,
 

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Discussion Starter · #6 ·
well that might make sense. as soon as i got the CEL i backed off the throttle and it went away.
 

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It may also have something to do with your egr being stuck open to. I think there's enough room to push on it carefully to see if it even moves. And while running to see if it has an effect.
 

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My bet would be a faulty EGR, or a bad temp sensor. If the temp sensor is bad, its telling the ECM your motor is still cold, causing the ECM to give it a too rich condition.
 

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Clean the throttle body and throttle plate with some carb cleaner and a toothbrush. Find the big (1/2) hose that comes into the TB from underneath at a 45 degree angle. The other end goes to the Idle air control. Pull this hose off the TB and spray a good shot of seafoam or pb blaster down that hose and reistall it. let it sit over night and see if it runs better in the am. it sounds like you have vacuum leak or a problem with the EGR if this doesn't make a big improvement. The throttle position sensor on these trucks is rarely an issue if left alone. It is only 3 positions. Idle, run, wot. Also check the big hose from the air cleaner and make sure there are no holes or cracks in it.
 

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My Trooper has the exact problem...when cold it fires right up and fast idles , as it warms the idle comes down to around 950 rpm's...you shut the trooper off and come back later and it always drops the idle right away and acts like it is fumbling and wants to stall..you have to keep the rpm's up and once you start driving it it goes away in around 45 seconds....I can tell you I have a rebuilt motor, all new lines, new TPS, did the PB blaster on the cold valve, fuel pressure reg, injectors, 02 sensor, cat, muffler, cleaned throttle body, new egr, bled radiator, have a return spring for throttle cable,......the only thing I haven't done is the temp sensor for the ecu...but the problem your experiencing is dead on to mine...it sucks...
 

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It might be the brain !!! I posted on one of these about when I changed body's on my amigo 91-92 body. I used the newer brain and it ran good. Until cruising on the hyway. Engine light was coming on pulling hills and stuff, felt like a power loss to. I put mt old 91 brain back in and then it started having that low idle problem. Only difference's on the 2.6 setups was the egr controls. The 92 had two micro valves controlled by the ECM. My 91 was just mechanical vacuum lines. Also the 92 had a map sensor which I hooked up, but don't think my older brain even aknoledged ???

I always figured my ECM was possibly damaged. But maybe it's just the vintage of the brain. Or something is burnt ?????
 

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Discussion Starter · #12 ·
As i said before, everything thats been done is within the last 3 or so months.

We cleaned throttle body and plate, replaced temp sensor, and cleaned egr.

Right now thinking it could be alternator, fuel pressure reg, or tps.
 

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Yep I just through that one out there for everyone to ingest. Keep working on the little things one piece at a time. You should be able to do a resistance check on the tps if you have a little volt meter... See if it has a dead spot right off idle!!
 

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Discussion Starter · #14 ·
Yeah I figure the little things would be easier to test than the ecu. haha
 

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I have dealt with this issue about 15 times since 1993 when I bought and started working on my first Trooper.... right around the time you were born. I could tell you what the problem is and send you the part to fix it as well but you won't like the price..... good luck chump.
 

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It sounds like the warm up valve is just stuck. It takes all night to cool off completely and open up. Then after your first drive it warms up closes down and depending on the temp out won't cool down enough to fully reopen.
Just for the record cause I'm irritated I was born in the early 70's lol
For some reason I feel better now.
 

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Discussion Starter · #20 ·
I have picked out a bunch of possible culprits:
ECU, fuel reg, fuel pump, fuel pump relay, alt, fuel filter, and check if there is oil in the dist.

Also I can smell the gas after I turn it off. Something is obviously not right but it really only acts up in the heat. Since it's cooling off, I may forget about it now.
 
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