need some help pin pointing whats going on,

issue is happening during acceleration, I would say feels like theres lack of fuel delivery. I could be wrong so dont take my word for it. Hasn't died though ...ill be pushing the throttle and on one of the strokes, it will feel like no there is no output or power but only for a second.

some notes on the motor
1) recently i unplugged the ACC fuse due to power drain issues,

2) swapped in new wires (due to one of the old ones being broken)
I unplugged the fuel injector when the wires were bad (just to back it out of my garage into the driveway)
..but after the new wires i had accidentally mis-matched two wires and also forgot to plug it back in (not sure if this matters but i fixed both properly after i noticed)
not sure if something like this could mess up timing but again it seems like this is sort of a timing / fuel delivery issue


3) put in a new pcv valve, and quick oil change (synthetic) and oil filter

4) engine is swapped into my 1975 truck so it is paired up with old fuel pump, fuel filter .. etc which i plan on replacing soon, even though i dont think this will fix the issue. was also going to put it new plugs and fuel injector cleaning ...also dont think this has anything to do with it.

5) the wiring is not very neat , i know for a fact the radio circuit is messed up because when i plug in the ACC fuse it makes the alternator not work. so now i fear that one of the circuits that is responsible for fuel delivery or overall engine operation / timing is just not working.


6) completely no leaks on the engine or trans ...tiny crack on one of the headers (cant even see it) but sometimes i can see heat coming out of it.

idk ...

 

Does this 75 truck have tbi injection? I would imagine it was carbed. Check fuel pressure and timing. If the engine was swapped from tbi car to carbed truck you need to make sure you have a mechanical advance distributor installed.

 

I agree, the truck was set up from the factory for a carburator and a non computer distributor, which means unless you modded the fuel system to provide the necessary fuel pressure the fuel injection needs, you are way lean.

 

it was def carbed no doubt about it.

Not sure what kind of distributor, its like a beige colored one ... seems to be the standard one. idk ill try and get a picture up.
How can i determine what type of distributor?
I'm pretty sure what ever distributor came with the engine, the guy used.

Ill swap the fuel filter out and put some fuel injector cleaner in and then do a fuel pressure test.
what parts would i be testing when testing fuel pressure? the ECU, fuel pump, injectors?
Not sure how to test timing, i'll have to learn but learning is mainly why i bought the truck.

 

When I took the spark plugs out a couple months ago to do a compression test, they didnt look bad ...they looked proper.
I can take them out again and see if your'e correct...

thanks for your reply.

 

http://walbrofuelpumps.com/walbro-gs...5lph-pump.html

 

well i need to figure out what the issue is hopefully not injectors, timing chain /belt, or fuel pump ... but its prob one of those. but i guess it wouldnt hurt to just buy all

 

I think i located the fuel test valve , is it right under the map sensor?
also what is the correct fuel pressure psi i should have? 1990 tpi 5.7l






so heres pics of the dizz , i would say thats a mechanical advance dizz correct ?
no vacuum things coming out of it not sure what else type of distributors there are.


ALSO id like to point out that the plug wire with the white paint on it is actually cylinder #8 and as i see on a lot of firing order diagrams for the firebird tpi, the orientation of the dizzy has #8 cylinder wire at the front of the dizzy but as you can see mine is back there more on the left.

Does this make any difference ? orientation of the dizzy?

 

Looks like it's been converted to tpi. That's not a mechanical advance distributor but it's correct for what you have. Check the fuel pressure and put a timing light on it. Also rev it with the light on and make sure it's advancing.

 

what kind of dizzy is it?

also wheres the fuel pressure valve? i found a valve with a cap under the map sensor ...looks like the fuel pressure valve, but not 100% sure tho.
what is the proper psi for TPI ?

 

It's a hei divorced coil

 

thanks man, got midterm exams coming up but ill try to get to work within the next two weeks and report back to this thread or maybe start a new, if i can find the problem.

is there anything wrong with me having a different type of fuel pump.. i know the firebird has a tank internal one but the one from my truck is external

another thing, as for all the components / sensors the ECU is responsible for... is their any way to determine if any are faulty or even not working? the under dash fuse looks kind of crazy wires are hanging down from the dash, ive got a few fuses unplugged, and as for the engine bay ive tried to clean up as best as possible (i think everything is plugged in)....

 

If you have fuel starvation under heavy acceleration or cornering. A surge tank or sumped in tank pump would the solution.
Using a scanner or tuner pro rt to communicate with the ecm or check engine light to blink for malfunction codes.