Simon928

Hey everyone. I recently changed all of the fuel lines on my 1984 US Auto using Roger's kit. After I got everything put back together, I started up the car and there was a significant fuel leak, but it was solved quite easily by tightening one of the clamps on the injector hoses on the driver's side. After that we looked around, there didn't seem to be any leaks, so we thought that everything was good to go. After doing a bit of driving I noticed a pronounced fuel smell from outside the car, so I put the car on jacks and noticed fuel in the place pictured below underneath the car. I freely admit that I'm a beginner when it comes to car mechanics, so I am not familiar with what this item is. Whatever it is, there is fuel coming from the inside of the hole and leaking outwards, which is what's creating the smell. The problem I'm having is that I'm not sure what the actual source of the leak is. I took the air filter box off and looked closely at all of the hoses that I replaced and all of the clamps that were put on, and there is no evidence of any fuel leaks from the top of the engine bay. Seeing the amount of fuel that has leaked out to the bottom of the car, I would imagine that there would be a fair amount of evidence visible from the top, but so far no dice. Of course the obvious step (to me, at least) would be to tighten all clamps and see where I go from there, but before I do that I would feel better knowing where exactly the leak is originating from. Could it be residual fuel left over from the leak when I first started up the car after changing the lines? That was about a week ago, so that seems unlikely to me. Is there something else above that hole in the picture that could be causing a leak that could be completely unrelated to the fuel lines being replaced? And should there be a plug or something where this hole is? Any of your expert advice would be greatly appreciated. Thanks!

M. Requin

Whatever you do, don't start that engine until you've figured this out, and when you think you have it corrected, start it outside, away from everything!

Leon Speed

That part is called the bell housing, if you remove it you will see the back of the engine, where the crank shaft attaches to the flex plate and torque tube. Nothing there which could leak fuel. It is however the lowest point near the back of the engine, so one of the hoses at the top rear of the engine is leaking. It is either the one between the fuel dampner and regulator or the one going to the fuel cooler. Easiest way to check is to wipe everything off with a rag, remove the ignition relay or fuse, crank the car (or bridge the fuel pump relay). Goal is to get the fuel pump running without trying to start the car. Then feel with your hands on the hoses and clamps for wetness. Fuel also "feels" a bit cooler.

Park the car outside first and have a (large) fuel extinguisher ready.

WallyP

As others have said, this is a dangerous and potentially deadly situation.

Any fuel leakage under the intake manifold will also end up coming out there.

I would recommend making a fuel pump relay bypass for testing - it will be useful several times in the future.

Get four feet of lamp cord (two-conductor stranded electrical wire used to hook a table lamp to the wall socket); two male 1/4" spade connectors; and a good-quality single-pole single-throw (SPST) toggle switch, with OFF and ON positions clearly marked.
Put the connectors on one end of the wire, the toggle switch on the other end. After you have finished with it this time, neatly coil the wire and keep it in the glove box in case the fuel pump relay fails out on the road.

Unplug Relay XVII (Fuel Pump Relay, 2nd relay from the right end on the bottom row) and look at the diagram on the relay to identify the terminals in the relay socket. Make sure that the toggle switch is OFF and carefully plug one of the connectors on your relay bypass into Terminal 87 (fuel pump), and then the other connector into Terminal 30 (power). When you turn the toggle switch ON, the fuel pump should run. The ignition switch does not have to be turned on.

(If you use the bypass as an emergency measure on the road to temporarily replace a non-functional fuel pump relay, use Terminals 15 and 87, so the pump will only run when the ignition switch is on.)

Move the car outside, well away from anything valuable. Get a large fire extinguisher and keep it handy. Have someone else dependable there. Get a good flashlight - not a 125 volt incandescent light.

Remove the air filter housing. Look for any traces of fuel leakage. Look carefully at everything that you have touched. If, and only if, you can find no trace of any fuel leakage, turn the toggle switch on and quickly look for and smell for any trace of fuel leakage. Be quick but thorough. Don't keep the fuel pump running for very long!

Simon928

Thanks for the input guys. I have a mechanic friend who's going to be coming over in the next few days and we'll do what you suggest. I really appreciate the suggestions and I'll let you know how it goes.

Simon928

Just an update on my fuel leak situation. The front end of my car was on jacks, and it looks like that was why I couldn't see any leaks from the top. Once I lowered the car I could see one of the lines at the back of the engine compartment leaking, so I tightened everything up and all is now good. No more leaks and no more fuel smell. Yay for me! Thanks for all your help.

WallyP

I recently changed the transmission fluid in the wife's Suburban. After working for a bit, it became obvious that disconnecting the transmission cooler lines at the front would be a four-hour job to disassemble the front end, then four more to reassemble. I cut the line in a readily-accessible spot under the engine instead.

When I started to reconnect the line, I took the easy way out and used a piece of high-pressure fuel injection hose, figuring that would never fail in such a low-temp, low pressure application.

Three days later, coming back from a late round of golf, the hose popped of of the tube, dumping the transmission fluid and stranding the wife and I on a dark rural road. I used the screwdriver on my Swiss Army knife to reattach the hose, and my son brought us five quarts of Dexron VI, and we were home shortly thereafter.

The point of this long story - the high-quality, high-pressure fuel injection hose that I used had two problems:
- The hose clamps were torqued pretty tightly when installed. The hose softened enough in use that the clamps loosened.
- The inside of the hose is slick.

Moral: Use fitting with barbs, and check the tightness of every hose clamp on your system after a couple of heat cycles.

Simon928

Will do. Thanks again for the help!