chaseincats

Hi all - I can't seem to track down where my gasoline vapor smell is coming from. Has anyone used one of those 'combustible gas sniffers' on amazon (like this) to track fuel vapor leaks down?

Me too! We'll see how it starts tomorrow morning as the final test. I bought a bottle of fuel stabilizer after I got out of the car today haha.

Update for you: It is very possible the issue the entire time was bad gas. I drive it rarely and haven't added any gas to the low tank since I was expecting to have to disassemble the rear again - the last time gas was added was (I believe) mid-October when the hose originally blew. I took it out today and it was driving terribly as it always does when the red fuel light came on so I added only a couple gallons to it (again, since I was expecting to have to drain the tank) and the car woke up after about 30 seconds. The AFR numbers returned to where they used to be and its power was back. The car still smells like gasoline which is possibly due to me apparently using 3/8 hose instead of 5/16. The final test will be tomorrow morning when I try to start it and we'll see if it's still a chore or if we are really back in business - I will report back. If the issue really was bad gas all along, I will be incredibly humiliated. On the road fuel pressure numbers: 30 at idle, 34-36 at WOT, 28 during engine braking AFR numbers: 13.8-14.2 idle, cruise 14.7, WOT 12.8 -chase

No worries - I appreciate any ideas to get this fixed. I installed the hoses/gauge/zip tied it to the windshield wiper last night so if I get home early enough, I'll take it out for some answers.

I've tested that before by pulling the oil pressure sensor plug, turning the key to 'on' and waiting until the fuel pressure gauge gets to 32 before starting and doesn't seem to make a difference for some reason. I'll grab some hose this weekend for sure

Tonight's update: Pulled all 6 plugs, laid them on the engine, and cranked the car - all have identical spark Ran it and listened to the injectors - all click to the same rhythm Pulled the PCV valve just for the hell of it - rattles properly Confirmed firing order Confirmed distributor hadn't moved (timing line I drew hasn't moved) Some notes about the engine - it is difficult to start if I don't manually trigger the cold start valve. Once it eventually starts it runs rough but smooths out after a few seconds. It will run the rich cycle and lean out as it warms up, so the injection seems to be working properly. @Captain Obvious @Zed Head - I think at this point this weekend really will need to be the 'get some long fuel hoses and take it for a drive' time

posted this twice somehow - please ignore this

Alright, so I just got back from a trip and did some work on the car (trying to avoid a gas shower if I can): Checked for vacuum leaks both smoke testing it and with carb cleaner Used a vacuum gauge and I'm sitting at 16" vacuum which is the same as it has been since last time I checked a few years back when it was running well Ran the car and pulled the injector power connectors 1 at a time and each made the engine run rougher until I plugged it back in - so we know all cylinders are at least working in some capacity Next steps: Go through the FSM's component checks via the ecu plug Pull the spark plugs and make sure all are firing with the same power Take a gas shower (grab the long fuel line and go for a drive with the pressure gauge) If fuel pressure is consistent, pull the fuel rail, put all 6 in individual cups, crank the engine - surely one (or many) are not working even though they're only a few years old Anyone have any other checks I should add to the list? EDIT: I pulled the spark plugs and all of them look good except for cylinder #5 which is CONSIDERABLY darker than any of the others. Could we be looking at our possible culprit? The car will start only with starter fluid the first time. After it is started once (regardless of the amount of time it is run), it will start on its own without issue. EDIT2: I pulled plugs 5 and 6, placed them on the engine, shut the lights off, cranked the car and they both are outputting the same amount of spark. I pulled the spark wire, put a screwdriver in it, then laid it against an engine bolt and the spark coming out of the wire when it grounds to the metal is however considerably stronger looking than what the plug is outputting.

Right - I just wasn't sure the method of doing it

That's a great idea since that is currently my exact setup. I'll give that a try this weekend - thanks for that

i snipped those off and soldered on new connectors there a few years back 😞. it definitely did make a huge difference though.

This is a dumb question, but I'm going to ask it anyway. Wouldn't holding the pedal at 3k in my garage be the same as driving around or does the pump work harder when the car is under load?

Thanks. All the sensors on the front and their connections are new. It really doesn't make sense to me that the fuel line blowing can suddenly make a car running great suddenly have an issue with the EFI connectors but stranger things have happened.

I'll give it another look, but nothing as of now and you can't smell gas. We didn't see any leaks when we were under the car with the pressure gauge over the weekend.

Ya, I'll give that a shot this weekend I'm thinking

Interesting - ill check on the egr No more front firing from the engine if you don't push it too hard The car's injectors are probably around 2 years old @Yarb - I had the injector plugs replaced/soldered/heatshrunk/wrapped in electrical tape a few years back Could the fuel pump be weak, or do electric fuel pumps either work full force then die?

I've smoke tested the car a few times and at this point we're all set in that department (the car will die if you pull the oil cap). Since the idle is actually lower than usual (600) I'd have thought it would raise if there's a new vacuum leak? Regarding the 2psi drop - I ended up checking it with a new gauge spliced in between the pump and fuel dampener (34 psi), between the fuel dampener and the metal fuel line (34 psi) between the metal line and fuel filter (32 psi). We ended up blowing out the metal rail with a mechanic shop's compressed air tank system and still sitting at 32 psi. The car has been at least weekly driven for the past 8 years so there wouldn't be anything in the line especially since you can get 40 psi out of the pump if you pull the fuel regulator hose. That said, the car is definitely slower even when that is pulled than when it was running properly. Any ideas?

It just hit me - the car idles at the same rpm it always has - between 600 and 800 depending on the season. If there was a vacuum leak, the idle would be higher - so it has to be a fuel delivery problem because I haven't changed the configuration of anything and the idle hasn't changed indicating a vacuum leak, right?

I was curious about that and so I blasted my engine with carb cleaner (with a fire extinguisher right next to me haha) and got nothing - but it might be time for the cigarette/hand pump vacuum leak test. That said, I had been in a situation where the engine acted like this before, and it was when an injector connector somehow had 2 seals in it and so wouldn't be able to be plugged in far enough. The injector could fire but did not get enough power to fire enough and so the car could idle but whenever you'd press the gas it was just anemic as hell...

I have a '78 so if front fire protection was added later-on, I should have it. I just went through the FSM's checks both with moving the flap and all of the multimeter tests and everything came out in spec

This is kind of my fault because I didn't explain the scenario that got me to where I am (since I was so positive it was a fuel pressure issue). I was driving when one of the fuel hoses in the back of the car (that I later learned was quite old) blew. The car lost power as expected since it wasn't getting the amount of fuel it needed due to the split hose. Looking on my AFR gauge on the dash, it went from 14.7 on the highway to 19, and was sputtering with no power. After trying the accelerator a few times with no improvement, I put it in neutral and killed the engine - coasting to a stop in a CVS parking lot. I turned the car on and it was front firing a lot - turning around I noticed a massive puddle of fuel spraying out from under the car - I turned it off immediately and called a tow truck. After getting the car home, I put it up on jack stands and changed the split hose (the only one I didn't change a year ago for some reason, go figure). The hose that I replaced hung a bit low (like I was talking about at the beginning of the thread) so I zip tied it up. I turned the car on and it was sputtering and front firing and later discovered that I zip tied it too high/tight and kinked the hose. After cutting the zip tie and re-hanging it, we were back to the 32psi we've been chatting about. Long story short, the car was running great in its current setup until a fuel line blew, causing it to do quite a bit of front firing on the highway, parking lot, and home when looking into the hose kink. I've heard front firing can damage the AFM, which is the only reason I keep talking about front fire. I can richen the car with the AFM (or the potentiometer) but that isn't solving the problem since it was running fine with the current configuration until this event with the fuel hose and the running lean/front firing as a result of the split hose only allowing a fraction of the fuel needed to keep a proper AFR entering the engine. I hope that makes sense @Zed Head?

Arg. Looks like I’ve hit a dead end with the fuel pressure then? Any suggestions on where to look? The car was front firing a lot when the fuel line blew and it ran very lean. Could the AFM been damaged by that?

I have some fuel pressure numbers for you. When I connected a fuel pressure gauge between the fuel pump and dampener in the rear of the car, I got 40 with the key off but pump on, and 34 with the car running with 32 psi reaching the front with the fpr vacuum tube on. Is 34psi out of the pump's fuel outlet while running correct?

It does but that makes me curious why it originally sat and idled at 36 psi before I messed with the hoses.

In the past, my idle was at 36 with the vacuum line connected but now its 30 and the car is running lean. I believe the FSM says it should idle at 36 too.