So more on this '84 NA I bought out of a barn. After changing both the clutch master and slave, flushing and changing all the fluids, and doing some interior wiring I decided I would try and crank the car over.

When I bought the car I was told it needed a fuel pump as it would only start using a can of ether. When I went to change the pump I noticed the tank was bone dry. So I decided to throw some gas in it and see what happened. Sure enough it fired almost immediately. But it only ran for about 5 seconds then sputtered out. Wouldn't start again, nothing. So the next day I decided to try again. Exact same thing: Runs for 5 seconds then sputters out. You have to leave the car sitting for at least 4 hours before it will run for its 5 seconds of glory again. Otherwise it just cranks.

I did change the relay with a new one. But I'm wondering could the pump be bad and only pressurizing the lines enough for a few seconds?

 

FPR?

 

Now that you mention it, when it is running the FPR is VERY loud. Almost sounds like a brutal valve tick but it's clearly coming from the FPR. There is also a small amount of oil residue around the FPR.

 

I've never had one fail but my guess was that it's keeping the pressure down so low the car is basically choking, dies. Like it's fighting the fuel pump.

 

I ended up swapping the entire fuel rail/regulator/dampener from my parts car (Was running fine) and no difference. Looks like tomorrow morning I'll just swap out the pump and filter along with all the rubberlines between from my parts car. See if it solves it.

 

Maybe the filter is extremely clogged

 

Check the exhaust for rat nests it could be choking itself out.

Had a 5.0 mustang that was left sitting for a year then put a junkyard 5.0 in it and mice had made a nest in the exhaust and the damn thing couldnt stay running.

While its running check to see if exhaust gases are coming out.

 

Oh, exhaust is definitely coming out. But now the starting for a few seconds seems to have stopped. Noticed the tach is no longer bouncing. Pointing to the speed/reference sensors. Which has presented a whole new batch of issues.

 

So far, I've changed the entire fuel rail including regulator and dampener with a known good one, no difference. Changed the DME relay, no difference. Noticed the tach wasn't bumping on cranking so I changed the speed/reference sensors with known good ones, no difference. All I have left to do now is swap out my fuel pump and filter (have a brand new filter and yea old pump) and see if that does it.

 

When you say no difference are you referring to the tach isnt bumping still?

did you clean out the gas tank before filling with new

 

Yeah, the tach still isn't bumping and the no start problem is the same.

As for the tank, I didn't clean it out. Probably should have. So hopefully the new pump and filter I pull off my old car will help.

 

why wouldnt you?

But if your tach isnt bouncing maybe there is more to the problem. maybe you have the sensors reversed

 

When I did the sensors I put them in the exact same way they came out of the running parts car.

the further into this car I dig, the more it seems someone has tinkered with just about everything on the car.

 

PO nightmares... I feel that

 

check the wires/ connector to your temp sender, I had this issue with my 83,

+1 on the tach bounce if the signal from the reference sensor is too weak it will not stay running, also make sure the intake is clear and no nests etc esp in the snorkel, my 924S ran horribly when i started it the a few weeks ago, there was a mouse mansion in the snorkel