1999 GM van with possible computer issues

indyrt

indyrt

Club Member
1999 chevy express HD 3500 (1 ton) van w/ 175K

Going backwards. it was not until today that my friend said, sometime when it rains, water can get into the computer and it will cause messed up issues. It rained last night.....

Today, the fuel / ? issue came back....when cold, it will almost not run in gear. Must be feathered out. When warm... it's gone. Fuel filter changed a few months ago cuz it war really running lean / started to detonate under load.

Last night the speedo started bobbing between 20 and 40, causing the trans to downshift. It guess there is an electronic sending unit for speed and the computer gets it's shift info there which, is wrong.

1) Can a plugged fuel pump cause pump to start going bad due to hi psi?
2) anybody know of this problem/s
 
sounds like there may be a few issues. hard to tell without playing with it
coolant temp sensor maybe the cold issue. if it has issues when wet it maybe a plug wire
speedo is probably a vss
 
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Have you replaced the distributor cap ? they are prone to micro cracking and wick moisture in and then have hard starts,missfire mostly when cold and damp out.


I have seen the PCM cases corrode and split open. It almost looks like they explode when they do it. I have seen similar issues when that occurs.

My gut tells me you most likely need a Vehicle speed sensor and a new distributor cap.

Sean

indyrt said:
1999 chevy express HD 3500 (1 ton) van w/ 175K

Going backwards. it was not until today that my friend said, sometime when it rains, water can get into the computer and it will cause messed up issues. It rained last night.....

Today, the fuel / ? issue came back....when cold, it will almost not run in gear. Must be feathered out. When warm... it's gone. Fuel filter changed a few months ago cuz it war really running lean / started to detonate under load.

Last night the speedo started bobbing between 20 and 40, causing the trans to downshift. It guess there is an electronic sending unit for speed and the computer gets it's shift info there which, is wrong.

1) Can a plugged fuel pump cause pump to start going bad due to hi psi?
2) anybody know of this problem/s
Click to expand...
 
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Make sure you use only AC-Delco parts. They might cost more but worth it in the long run . Cheaper one break down too quickly.
I agree igniton issue. Fix that first then you can check evrything else. Fuel pumps work or they don't.
 
chuckycaprice said:
Make sure you use only AC-Delco parts. They might cost more but worth it in the long run . Cheaper one break down too quickly.
I agree igniton issue. Fix that first then you can check evrything else. Fuel pumps work or they don't.
Click to expand...


x2 AC Delco parts only
 
1999 van issues

Well, the computer box was split open and apears to be the problem. It DOES need a tune up, I've owned it for 50k and done nothing.

What tells me it is mostly computer is:

The trans was freaking out ONLY when the speedo started bouncing (30-40 mph)... it then falls and the trans would free-wheel for a second. The anti-lock light came on. But soon as I stopped, no problem till the speedo bounces. Trans problems are usually a constant as it is mechanical. It COULD be a speed sensor but the other issues and look of the computer tell me that is more than likely it or most of the prob.

I heard G&T auto has computer. They said a new one would need to be flashed.
Can I take a new one to a speed shop and have the set it up better????!?? Than mr dealer guy???

Thanks

RT
 
GM parts

PS... delco spark plugs made 5 hp over others on Worlds prostock motor. They will be in my ford! ha
 
Replace PCM and go forward. Yes it will need to be reflahsed. You are better off going to a reputable parts place that sells standard ignition parts and getting a PCM becuase they can flash it for you onsite.

Sean


indyrt said:
Well, the computer box was split open and apears to be the problem. It DOES need a tune up, I've owned it for 50k and done nothing.

What tells me it is mostly computer is:

The trans was freaking out ONLY when the speedo started bouncing (30-40 mph)... it then falls and the trans would free-wheel for a second. The anti-lock light came on. But soon as I stopped, no problem till the speedo bounces. Trans problems are usually a constant as it is mechanical. It COULD be a speed sensor but the other issues and look of the computer tell me that is more than likely it or most of the prob.

I heard G&T auto has computer. They said a new one would need to be flashed.
Can I take a new one to a speed shop and have the set it up better????!?? Than mr dealer guy???

Thanks

RT
Click to expand...
 
1990 van

Well, it fires and quits. It had this issue over the summer. It came and went at diff. times. When cold, it would act like not getting fuel. I could feather it to get going. When warm it was ok. One time I could not lean into it as I was getting detonation. I changed the fuel filter and it seemed better.... Went away. The other day, it came back to hard starting cold. NOW, because it is SO cold, it REALLY won't start. EGR valve looks ok... I'm pluggin it while off. I have a cap / rotor.. ane site said coil and they could see an arc.....???? ERRRRRRRRR

HHHEEEEEEELLLLLPPPPP!
 
is the security light comming on and flashing ?


indyrt said:
Well, it fires and quits. It had this issue over the summer. It came and went at diff. times. When cold, it would act like not getting fuel. I could feather it to get going. When warm it was ok. One time I could not lean into it as I was getting detonation. I changed the fuel filter and it seemed better.... Went away. The other day, it came back to hard starting cold. NOW, because it is SO cold, it REALLY won't start. EGR valve looks ok... I'm pluggin it while off. I have a cap / rotor.. ane site said coil and they could see an arc.....???? ERRRRRRRRR

HHHEEEEEEELLLLLPPPPP!
Click to expand...
 
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