240 Fuel Issue
 

Hello all, I need some help for my 87 240 5 speed sedan.
I was leaving class last night and when I started my car it started up within two cranks. I immediately knew there was a problem since I've had for 3 years and it never starts up that fast from dead cold. It was all fine at first but the idle started to dip and fluctuate a little and when I started to pull out the engine was chugging a lot and very hesitant under acceleration. I got it home thinking it was the mass air flow sensor and tried disconnecting it to see if it would stabilize. It wasn't much better but it was definitely an improvement over what was going on. The hesitation under acceleration went away and the chugging wasn't as bad.
I drove it to BapGeon this morning to get a new mass air flow sensor with the old one disconnected. Once I got there I removed the old sensor in the parking lot but while I was under the hood there was a strong odor of fuel coming from the engine. In the hope that this would be solved with a new MAF I went in for the new one, spared some throttle body cleaner in my intake, and installed the new MAF.
The idle was better and so was the hesitation was gone but, the idle was still not what it was suppose to be and the car was doing some frequent jerking on the interstate ride home.
When I got back I disconnected the fuses for each fuel pump to see if things changed and they got a little worse each time. After putting the fuses back in the the car won't start. I try a few time and get not a single spark. I pop the hood and the fuel smell hit me and I see gas dripping from my idle air control valve so I'm flooded.
I've never had an issue of needing to run with a quarter tank or more and usually never filled up unless I was at the red box on the gauge. The fuel filter and o2 sensor were changed in the past year and my mpg was normal until last night where it seems I've lost about quarter tank or more in about 40 miles from half tank.
I believe I could hear the main pump running fine before the intank I can't hear from the drivers seat.
Does it should like an intank pump problem or just a little overuse of gas from a not having the MAF in there?

sounds to me like a stuck open injector, maybe the cold start injector? or a blown fuel pressure regulator, squirting gas into its vacuum hose, and thence into the intake manifold.

but I dunno, can't see it.

there's only one fuse for the in-tank pump, the main pump is on the same fuse as the rest of the injection system including the ECU, thats the 25A blade fuse near the battery. both pumps run together.

the symptoms of a bad in-tank pump are fuel starvation at higher throttle settings when the gas tank is low, getting worse as the gas gets lower. above 1/3rd tank, you'd hardly know the intank was dead, except your main would be working extra hard and probably noisy. the symptoms of a bad main pump are an engine that won't run at all, or if the pump is bad intermittently, an engine thats hard to start, but usually keeps running once it does start.

re: that fuel pressure regulator... disconnect the vacuum line, is it soaked in gas? have someone crank the car while you're watching it, does gas come out the vacuum nipple on the back of the FPR ? if so, then its definitely bad, and should be replaced ASAP. probably should replace that vacuum hose, too.

Thanks a bunch. I only just managed to get to Bap minutes before closing so I forgot the vacuum hose but I can grab a nice one from advanced. When I tried to start it with it off so much gas can out of the regulator it was ridiculous. I'm all changed out now though. Thanks a lot.

those regulators have a diagrapm in them, when that fails, 50+ PSI of gas flow from your pumps just rushes through.

the vacuum connection is used to modulate the fuel pressure according to vacuum. high vacuum == less fuel pressure, no vacuum (wide open throttle) == more fuel pressure.