1988 3vze no more than 6000 miles on professional rebuild. Injectors cleaned and tested at time of rebuild no issues.

symptoms:

ran fine two days ago then:

starts fine cold until ANY throttle input then it loses all power and barely idles at 100 rpm, once it reaches operating temp idles terribly but will rev up to 2200 rpm then acts like its being limited there, laggy throttle response at all temps. when ignition is turned to "ON" fuel pump runs continuously, i can clearly hear the fuel being sprayed into the cylinders. all 6 spark plugs are fouled, looking into the cylinder all I see is black soot. after shut down i can hear fuel in the lines dumping into the engine until the pressure equalizes in the system.

what I have ruled out:

No vacuum leaks, initially I thought I had a major vacuum leak but a bottle of starting fluid ruled all that out. I haven't checked timing but I cannot turn the distributor so IMO I don't think timing is an issue. obviously fuel pump is working. fuel filter was changed when the rebuilt engine was installed.

So...

looking for more input, I guess I am a little overwhelmed as to how many things can cause this issue. First thing that comes to mind is that there is a sensor telling the ECU/EFI that the engine is in a overheating condition and is dumping fuel in. along those same lines maybe there is a wiring issue. before i start replacing all the temp sensors and senders can i test them? anyone have a table of values for them? or even better does someone know a cause that is super duper simple?!

Thanks in Advance!

Signed,

a poor college student in a catch 22 kind of situation

 

I use my '93 FSM all the time, except for this troubleshooting tree HERE ... I've never used it, but it looks useful. I'll keep looking for solutions in the meantime. I'm a better researcher than I am a mechanic so ... good luck!

 

And HERE's the troubleshooting guide for the MFI system.

 

Thanks bluAM2. I came across the MFI troubleshooting guide earlier this morning when searching for answers to my problem, doesn't look like much fun...the other guide looks helpful too. I probably wont get around to messing with this stuff till after Christmas but i'll stockpile all the info I can!

 

"doesn't look like much fun..." You can say that again!

When you say "when ignition is turned to 'ON' fuel pump runs continuously, i can clearly hear the fuel being sprayed into the cylinders..." do you mean while the engine ISN'T running, but the key is turned to "ON" you can still hear fuel being sprayed? Merry Christmas to YOU ... OUCH!

 

correct while the engine is not running its pumping fuel in.

this is how EVERY plug looks as well as the top of the pistons:

 

Fuel pump maybe? http://personal.utulsa.edu/~nathan-b...28fuelpump.pdf

 

I just dont think the fuel pump would cause my issue but I have been wrong many times before.

 

So the VAFM is bad, im showing over 400 ohms of resistance between e2-Vs and a reading of zero between Fc-E1 when it should be inifinity in the fully closed position. looks like im on the hunt for another VAFM!