1989 Grand Marquis ECM removal

[monotonorobo]

If you wish to check for vacuum leaks, the best way is with a smoke detector or spray carb cleaner on all the vacuum lines (be VERY careful around a hot engine) and listen for idle changes.

Yeah I can’t do the carb cleaner trick, can’t get it to run long enough, or get it to start enough times to do it. I’ll try it with smoke.

[monotonorobo]

I was about to take off the fuel rail and check if the injectors were leaking but I broke one of the bolts so it’s stuck on for right now. Any other way to tell if it’s the injectors?

[gadget73]

put a fuel pressure gauge on it. if the injectors leak, the gauge will not hold. Of course if the check valve or the fuel pressure reg is bad it does the same thing. Or just pull the plugs, if one is wet and gassy, there you go.

[monotonorobo]

Got it. I knew that plugs being wet meant too much fuel but I didn’t know it meant the injectors were at fault.

[gadget73]

doesn't absolutely mean its injectors but its a pretty good clue something is wrong.

[monotonorobo]

doesn't absolutely mean its injectors but its a pretty good clue something is wrong.

Did some research and also thought about it, new fuel injectors came in and I decided the check the spark plugs again and this time instead on just a few smelling like gas, all 8 of them smelled like it. So now I believe it isn’t a fuel injector issue at this point. I’m thinking FPR because when I check the fuel rail after priming there’s little to no pressure. Would just like to ask what do you think of the issue?

[sly]

Yeah... if there's no pressure after priming 2-3 times, there's something in the loop that's bad. If using a gauge, watch the gauge as it primes the 3rd time if you can - if it doesn't go up to about 40psi... FPR is probably bad - replace that and you should be good. If it does go up and immediately drops back down, the one-way valve in the fuel filter is bad and possibly a leak in the fuel pump hose inside the tank. But since that's a real PITA to get to as it's on the side of the tank against the trunk, try replacing the fuel filter first.

If it is a rupture in the hose from the fuel pump to the hanger inside the tank, that will prevent pressure from building in the first place and you will get little to no flow through the system. You can pull the line off the fuel filter and catch into a gas can and cycle the key to see if it's spraying out like mad as it should, or is a weak leak. This would indicate fuel pump issue if it's not spraying real strong. This is probably a two person operation as well.

[monotonorobo]

Yeah... if there's no pressure after priming 2-3 times, there's something in the loop that's bad. If using a gauge, watch the gauge as it primes the 3rd time if you can - if it doesn't go up to about 40psi... FPR is probably bad - replace that and you should be good. If it does go up and immediately drops back down, the one-way valve in the fuel filter is bad and possibly a leak in the fuel pump hose inside the tank. But since that's a real PITA to get to as it's on the side of the tank against the trunk, try replacing the fuel filter first.

If it is a rupture in the hose from the fuel pump to the hanger inside the tank, that will prevent pressure from building in the first place and you will get little to no flow through the system. You can pull the line off the fuel filter and catch into a gas can and cycle the key to see if it's spraying out like mad as it should, or is a weak leak. This would indicate fuel pump issue if it's not spraying real strong. This is probably a two person operation as well.

replaced the fuel filter few months back but it coulda went bad again. They sent me fuel filters for a g body like 4 times so I’ll see if I can fit one of those on it. I’ve dropped the tank and replaced the tank itself along with everything in it besides the vent valve thing. Also, FPR is supposed to have gas come out once you take the connection to the intake off, right? It did that the last time I replaced it, but that was when I also had a bad fuel pump & filter.

[sly]

If fuel comes out the top where the vacuum line is, the FPR is blow out. Fuel should NOT come out of that hole. Vacuum helps vary the pressure between about 32 psi at idle (high vacuum) and 40 psi at wide open throttle (or no vacuum).

[monotonorobo]

Fuel didn’t come out of this FPR though, it was the last one and I just wanted to know if it was normal. And I can only test so much since the car only starts sometimes then dies. Usually after sitting for a few hours.

[sly]

Sounds like the FPR you have is probably good as far as the diaphragm is concerned. No fuel pressure is an issue though. It could still be having an issue of allowing too much fuel to return. Try the trick of disconnecting the fuel filter at the tank side and see if you get really good flow out of it (safely if you can - put the hose into a container to catch the fuel). It should be spraying really good for the second or two it primes with just key on. If we can eliminate specific items first, that would be better. If it sprays good to that point, put the fuel filter back on the tank side and disconnect the engine side from the filter (other end) and try it again. If you have poor flow, replace the filter... if the flow is good, then you may have a FPR that's not allowing pressure to build up.

[monotonorobo]

messed around a bit after work today and I believe it's either the fuel pump or the fuel pump relay. Took the tank end of the fuel filter off and primed it 4 times, no gas whatsoever. Still don't get how it ended up running rich too at the same time. Also, heard the fuel pump whistling but no gas.

[friskyfrankie]

Should you decide to change the pump, do the relay as well.

[gadget73]

if the pump runs, its not the relay. If it runs and you get no pressure, likely either the line in the tank is split, or the regulator is stuck. More likely the line in the tank. Or I suppose the filter could be plugged solid. Can always unhook the filter and stick the line into a catch pan. Turn the key on and see if it pumps.

[monotonorobo]

Yeah I’ve already unhooked the filter on the tank side. I guess I’ll have to drop the tank again.