Hey guys and gals, trying to help out a buddy with his car, It's kind of a weird problem to explain so I'll tell you what he told me.

(begin quote) "My friend drove the car and down shifted he said and it started f-ing up he called me and said it had a really bad miss so he thought it needed spark plugs i got it home went threw it bought new plugs and s--t and it wasnt it..

The car acts like its starving for fuel so i put another fuel pump in and a fuel pressure regulator.Still does the same ****..

I checked the injectors and they seemed fine..

I was messing around and put a hose clamp on the return line off the regulator but not closed and it started my car lets me rev it but it still ****s up idk its hard to explain..

but if i take the clamp off the hose then my car wont start and idle idk ????" (end quote)

He's had like 4 diffrent people look at it with no luck. Any help you guys could lend would be a great help. He needs to get his car running in order to get a job so help a brother out. Thanks guys let me know what you think.

 

could be a clogged fuel filter
that's where i would start... probably needs to be changed anyway.

 

I think it has a newer filter in it when th e swap was done. Not sure tho I'll suggest that to him.

 

Is the CEL ON?

What is the quality of the spark at the plugs (bright white/bluish or weak orange)? When was the last basic tune up? Has he inspected the spark plugs, distributor cap, and rotor for wear and corrosion? When were the plug wires last replaced?

Has he checked whether the timing belt slipped a tooth (cam and crank no longer perfectly synchronized at TDC1)?

 

Definitely check the cam timing, as a sudden decrease in performance like this can be caused by the belt skipping a tooth.

If it doesn't idle well, disconnect the fuel injectors one at a time to see if it is a dead cylinder or a general misfire. If it does idle well but won't drive I would be inclined to agree that the fuel filter could be clogged, regardless of how new it is. This can happen very quickly if there is dirt in the tank.

If you disconnect the return hose you can confirm the fuel flow through the pump and the filter. It is best to just click the key on and prime it rather than starting the engine with the hose disconnected and potentially spilling gas everywhere.