Diagnostics

My Fiero is still down. I'm going to have some time this weekend to work on it but I need some information to help me diagnose the problem.

1. What should the compression be on each cylinder? (86 Tech4)
2. What is an average/acceptable psi for the fuel line?
3. Is there a way to check if the oxygen sensor is working properly?

Hopefully I'll get the car running better this weekend. Its not insured so I won't have it at the car show, but I hope to be there and meet up with some of you guys.

The car is running. It starts and idles fine, but violently hesitates or "bogs" through the mid rpm's. Once you get it up to around 3000 she runs clean. Although once on the highway it's as if there is a limiter on the engine as it doesn't pull any harder past 3000. Where as normally after 3000 the car takes off and pulls VERY strong.

I just hope it's not that stupid fuel tank sock, or the pump itself. I had no idea how I'd change those.

You're running really lean.

Pulling the MAP sensor line off tells the ECM (falsely) that you've got the gas pinned to the floor, or more accurately, that you've got an extreme load on it.  So it dumps in more fuel.

I say you've got a gimped TBI unit, injector, or the filter sock is clogged, or the pump is trashed, or the filter is clogged, or....   shall I go on?

Just checked the fuel pump by installing the pressure gauge in the fuel line before the fuel filter. The first time the key was turned on it pressurized to 25KPA or 3.5psi, then dropped, and the next three times it pressurized only to 20KPA or 3psi, then dropped.

Is the low fuel pressure most likely my problem?

I'm going back out the check the compression of the engine, I'll post my findings when I'm done.

I don't understand. I tested the fuel pressure before it even reached the TBI, which says to me the problem is the fuel pump.

If you're mostly sure its the intake the is the problem I know where I can grab a Holley TBI for an 86 Fiero.

Ok, I'll go and try that right now, although my gauge only gets to 10psi or 70KPA. I'll post the results. 

Does this mean I should replace the fuel pump or the TBI?

And make sure you only get a DELCO pump...  or you might be doing the job again in the next year or less....

Dr.Fiero wrote: And make sure you only get a DELCO pump...  or you might be doing the job again in the next year or less....

Here's what I've got so far.

1. Canadian Tire doesn't stock them or order them in
2. Wakefield and Sperling has a "Delphi" for $69.99 and a "Carter" for $89.99 and the sock for $9.99
3. Napa can order in a "Master" pump for $90.00

I can't find a "Delco" pump.

....funny

Thanks for the info. Lordco has one for $85.09 and yes I knew AC Delco was the GM standard. Also as far as I've found "Delphi" is another name for "Delco" Although I'm going to check to see if they are the exact same part numbers. If they are, I think I might try the Delphi pump for $15 less, seeing as I'm just going to have to change it again soon anyways. Maybe I can give you some free lessons on how to do it quickly? Or maybe you can show me at a tech session in my driveway? Either way, Johan will have to be on the road soon, I'm moving at the end of August!

 
AC Delco = Albert Champion Dayton Engineering Laboratories Co.
Johan =  Johan van der Smut from Goldmember = My gold 86 2M4