Little bro called me up today! Was driving home about hundred miles and truck started acting up/missing.....stopped and truck REAKED of raw gas! He didn't notice it leaking from the exhaust manifold where it meets head until the next day when it was cold.

So....he's got raw fuel leaking at the drivers side front hole and the two rear holes on the passenger side!!

odd thing is he said if he drove about 85+ or at high rpm in any gear it seemed fine....

truck is an 87 short box stepside 3o2 h.o. 4 speed.

I can't percieve how it could be some ignition deal where 3 holes aint getting spark unless its revved out. So im leaning towards a fuel injector issue? maybe stickng on?

anyone know possibly how the injectors work? if theres a brain box or maybe the three bad holes are on the same circuit maybe etc?

any help or ideas appreciated!

 

Sounds like dead cylinders or over fueling, as you stated. Check the oil to see if it smells of fuel also. Thats more for your lubrication and engine safety.

Injector are an electronically controlled valve. The computer is the brain box in an EFI engine. It tells the injector when to fire. I work on diesel engines in which there are moving parts inside the injectors but id assume you could also have a stuck open with a gasoline injector as well in which the fuel is dumping in. If this is the case the fuel is probably exiting through the exhaust valves and leaking out the manifold and also being blown out through the tailpipe.

Check and see if you have spark in those cylinders. As for checking injectors, maybe someone else can help. Like I said before I am not too familiar with gasoline injectors so I am not sure how you go about testing those. A diesel is a little easier..

 

Can you be more specific about where it's leaking, I have a hard time believing there would be raw fuel comming out of the cylinders so it could just be bad O-rings on the injectors or there could also be a rust hole or crack in the fuel rail.

 

Sorry Paul, your wrong. I have a 1990 F350 XLT that has the same problem. Before I replaced and resealed the exhaust manifold, there was fuel spraying out of the seam where the gasket should seal the #2 port. New fuel injector in the #2 made no difference. Now that it is sealed up, I get gas seeping thru the seam on #2 and then to a smaller extent, #3 and a lot out of the tail pipe. I put my hand over the #2 EX port so that it covers the top and both sides. There is no fuel sprayed on my hand. Naturally, we don't run it very long because of the fire issue. The rails and intake manifold are dry. No fuel under the truck except for under the tail pipe. Compression is at 155 to 160 on all 4 of the cylinders on that bank. I will try asking shanes66charger what they found. I realize this sound like a bad joke but, this is not only my everyday vehicle but my home is in the bed. A Lance 855 camper.

 

Same question to your sir. Were you able to figure out what was wrong with your brothers truck?
I have a 1990 F350 XLT that has the same problem. Before I replaced and resealed the exhaust manifold, there was fuel spraying out of the seam where the gasket should seal the #2 port. New fuel injector in the #2 made no difference. Now that it is sealed up, I get gas seeping thru the seam on #2 and then to a smaller extent, #3 and a lot out of the tail pipe. I put my hand over the #2 EX port so that it covers the top and both sides. There is no fuel sprayed on my hand. Naturally, we don't run it very long because of the fire issue. The rails and intake manifold are dry. No fuel under the truck except for under the tail pipe. Compression is at 155 to 160 on all 4 of the cylinders on that bank. I realize this sound like a bad joke but, this is not only my everyday vehicle but my home is in the bed. A Lance 855 camper. Like so many of the folks here, I have been working on cars and trucks most of my life, as well as the 6 years I was n the Corps, but, this one just doesn't make any sense.

 

Far as we could figure the temp.coolant sensor somehow shorted out and wasdumping max fuel. That didnt fix it first but we stopped seeing raw fuel. Finally it dawned on us to check fhe spark plugs......they were wasted, not sure how it still ran lol

He dont drive it much but seems to be fine now.

 

Both of you guys have a serious problem with your trucks. If there are no apparent fuel leaks on the exterior of the motor then one or more fuel injectors are leaking internally either because they are dirty and stuck open or because there is a short in the injector wiring causing it to be held open electrically. The spark plugs should tell you which cylinders have the problem.. or if you actually have gas pouring out a cylinder then it should be pretty obvious.

 

Thank you for your help. That wasn't the problem for me though. The fuel pressure regulator was bad. The injectors are spring loaded and the ones closest to the regulator were being forced open. Had friend tell me a week later that he has seen the same thing on another Ford truck years ago. We live and learn. Here is another for the memory file that we may never use.
Thanks again.

 

Sir,
Your belittling us is of absolutely no use to any one here. Many, many people are more than willing to share here and give others advice and help with squirrely problems like I had. These folks are Awesome for being willing to help and I for one am and will always be grateful for their willing help.
You sir, were of no help to anyone. If you want to help, great and thanks but, what you offered was of no help to anyone but your ego. Since you had no idea what the issue/problem was, maybe you should have just kept quiet. I couldn't believe that what shouldn't ever happen, was happening. Some people thought I was nuts. Rest assured, I am not nuts and sure as I am sitting here typing this, it was happening. It was a $23 part and it took about 45 min. to burn all of the fuel out of the exhaust system.
Have a good day my friend.

 

The fuel injectors cannot be forced open. High pressure actually forces the injectors shut.

The most likely thing happening is your fuel pressure regulator diaphragm ruptured and it was dumping raw fuel into the intake manifold through the vacuum line.

 

That vacuum line was clean and dry. No fuel trace in it and no smell of fuel. Checked all the vacuum lines for signs of fuel and nothing to be found. The fuel was only on the left side where the regulator is. I could see it seeping out thru the EX gasket on the first 3 cylinders on that side. Everything else was dry. Before I changed the EX gasket and resealed the manifold, gas was spraying out of the #2 & 3 cylinder, between the head and EX manifold. But thanks for your help. Any help is appreciated. Have a great week.

 

And removal of that very large chip from your shoulder would be advisable as well.

Nobody has "belittled you" by saying that a very serious problem exists.

You can do that "sir & good day crap" till the cows come home, it will win you zero respect or admiration in the end.

 

You sure are a wonderful person aren't you? You are like the other guy. You offer up foolish words but absolutely nothing to help anyone. Just like the other guy. A little bit of advice, sir, respect freely given should not be disrespected the way you do. Did I miss it when someone asked you to toss in your two cents? Exactly what do I have a chip on my shoulder for? You seem to have lots of knowledge without having any information to go with it.
I believe that Conaski can speak for himself or did he ask you to make this response for him?
A Fuel Pressure Regulator that has a malfunction is not a "serious problem" with an engine.
Again, I thank shanes66charger for his help. He did get me going in the right direction since the injectors, wiring harness and vacuum lines all checked out good. In fact, I just replaced all of the vacuum lines at the beginning of this year since they were falling apart.
In fact, I thank everyone on this site that has offered up advice and help with the issues we have with our trucks. I have already found a great deal of valuable information here to help with my old "BAT", (Big A$$ Truck). Thank you very much folks and have a great week.
You too Mr. Scndsin.

 

Welcome to my Iggy list...

 

I had a "stuck open" injector on my 1995 f150 xlt super cab. Red in Color. Under The engine bay was a 5.0 302cid engine. Behind was an aode. 2wd

I dumped out just about 2 gallons of fuel/oil from the crankcase. I removed spark plugs
On all cylinders. Number 3cylinder plug was WET with fuel.

I removed some crap then the plenum. popped off the fuel rail and dropped in an injector on #3 ONLY.

Cleaned the fouled plug. Changed oil filter and oil and buttond her up.

I drove it like i stole it. Went home checked oil and checked the tailpipe. No gas!!


Do you know what caused all that? No. you dont so let me let u in on it.....

Raw fuel!!

It was coming out my tailpipe.

Guess how i diagnosed and fixed the issue?
With the help of this board and people like conanski that share alot of valuable information with us. (me and other people on this board).

Not every one is going to have the right answer or diagnostic to help fix your issues at hand.

That was just a stupid comment on your behalf.

I hope i provided enough information.

She was a beast till 2months ago,after that repair was done.

I never messed with the fpr or coolant sensors. the one by the thermostat is for the computer other is for gauge. I only changed 1 injector.

I am a witness it can get stuck open.