88 chevy

[JHH]

Ok I have been fighting an 88 chev full size 4.3 65,000 miles

customer brought it in and truck ran rough, Had new plugs,wires,cap,rotor,ECT sensor,fuel filter,IAC valve.I diagnosed by shorting cyl and compression test that #3 cyl had problem. removed head bad valve, had head and valve repaired. put truck back together and now it wont idle unless I pull the vac hose off of MAP sensor. Then truck runs good but rich. replaced sensor (knew better) no help.

I have NOT taken fuel PSI check I pulled intake back off thought that I had a restiction because of vac gauge being pegged (29in) I have to put intake back on first to check it

Any other suggetions? Any one else have problems simmilar?
Any help is apprectiated. JHH

 

[Saltydawg]

Ok I have been fighting an 88 chev full size 4.3 65,000 miles

customer brought it in and truck ran rough, Had new plugs,wires,cap,rotor,ECT sensor,fuel filter,IAC valve.I diagnosed by shorting cyl and compression test that #3 cyl had problem. removed head bad valve, had head and valve repaired. put truck back together and now it wont idle unless I pull the vac hose off of MAP sensor. Then truck runs good but rich. replaced sensor (knew better) no help.

I have NOT taken fuel PSI check I pulled intake back off thought that I had a restiction because of vac gauge being pegged (29in) I have to put intake back on first to check it

Any other suggetions? Any one else have problems simmilar?
Any help is apprectiated. JHH

Which type of fuel pressure regulator does that 88 4.3 litre have?
The later model ones have a fuel regulator that is located under the upper intake manifold and is prone to leaking. If t does leak it dumps raw fuel into the manifold and causes poor running.

 

[JHH]

No that isnt leaking. It is located in the throttle bdy itself. I think I have overlooked the problem but wont know till I put the intake back on. (Fuel psi)

Just thought I would see if any one else had similar problems.I should be able to figure this out I worked for a G.M. Dealership
for 15 years. I quit and had my own shop till the new year when My old boss called and wanted me back to help train kids out of tech school in shop. Here I am trying to train kids and cant even find the problem on 88 chev let alone the 06 duramax.


JHH

 

[JHH]

Just got through checking and replacing fuel pump on this truck. That fixed it. I only had 3 1/2 psi fuel pressure.

JHH

 

[Saltydawg]

Yup that'll do it hehe.