92 mtx, please help

[SedanHatesOwner]

car has 112k on it, heres the deal, i had to replace the fuel pump, cleaned tank, replaced fuel filter, etc... car will idle all day, and run fine, but after a load is put on the engine, for example, up and down the driveway, when throttle is applied car will not rev past 3k and if more than 1/8 throttle is applied the engine bogs out. but will still idle ok. if i shut the car off, and then restart, it will be fine again, untill a load is put on the engine. please help

 

[ycode90]

check for codes,
Search.

 

[itwonder]

www.shophoenixproject.com Run KOEO and KOER tests, report codes. Quick thing you can try is unplug the MAF sensor and see if it runs better.

 

[SedanHatesOwner]

Maf makes no difference. Ordered cam and crank sensor hoping to come up with something. Thank you for replys all info is much appreciated.

 

[zach44102]

vaccum leak?

 

[zblackbeast]

Throttle position sensor im thinkin..

 

[stangeater]

Did the problem only start after you replaced the fuel pump etc?? If so, maybe your fp is faulty, or you hooked something up wrong?

 

[zblackbeast]

IIRC he fuel pump is always pumping at max capacity.. SO, as long as its idling and getting fuel to the rails i highly doubt that there is something wrong with the pump itself.

 

[SuperHO]

what fuel pump did you replace it with? did you drop the tank or cut a hole? was there anything else done to the car at the time besides the fuel pump?

 

[zblackbeast]

Tim, am i correct about the pump tho? I can't remember correctly and do not want to give false information.

 

[frosho]

That doesn't sound right. If the pump is weak (i.e. not providing full pressure), it will only be able to supply a certain amount of fuel. The higher the load on the engine, the higher the fuel demand, so theoretically it should run worse and worse as the revs rise. Idle speed would have the lowest fuel demand (other than coasting, when the injectors aren't firing).

Test the fuel pressure at the rails. This should tell you whether or not it's a fuel supply problem.

 

[zach44102]

maybe try running through a bottle of fuel injector cleaner....is it possible the injectors are so gummed up its not getting a full spay?

 

[luigisho]

clogged cats?

 

[Vnuk1]

Dude needs to pull his codes to make any accurate diagnosis..

 

[SedanHatesOwner]

its definitly a electrical issue. no check engine light but as i said before when it messes up i can shut the car off and start it right back up and its fine but messes up under a load like loosing voltage maybe.

 

[zblackbeast]

i still stand by my original idea.. Unplug the TPS and see if it does the same thing. I once drove my SHO and forgot to plug that puppy in and yeah.. it was NOT a happy camper.. I also had the MAF unplugged too.. so im sure those two things together and i mad the SHO want to drive off a cliff..

 

[itwonder]

Another simple thing to check. Spark plug firing order. Search forum for diagram. It is tricky and easy to get two crossed.

 

[SedanHatesOwner]

No engine codes. Fuel pressure dropping off when messing up. Fuel pump is on at all times (tested with stethoscope on fuel tank) I'm thinking bad regulator at this point. No change after replacing cam and crank sensor.

 

[SuperHO]

again...what brand of fuel pump did you stick in there? did you drop the tank (thus possibly pinching a line) or cut the hole under your back seat?

 

[Lorenr]

Check That Fuel Pressure

I've had this happen with a brand new fuel pump before. I blamed everything else because it was a new pump and didn't think that would be it especially, because it worked fine for two or three days.

The fuel pressure gauge is the key and the fact that you did not replace the regulator. I can't remember what the fuel pressure is supposed to be but I suspect it is required to be about 45 lbs. If it drops off at throttle then I'd first R & R the pump. Then maybe the regulator, but regulators don't usually go bad.

Over the years I've SLOWLY learned (I don't know why it takes so long) that when something goes wrong to go over the most recent work again. Also, only change one thing at a time.

:swing: