Engine Car spewing fuel

silverlx50

Active Member
Apr 4, 2007
122
50
38
I'm trying to diagnose a fuel problem. My car basically went into limp mode and was spraying fuel out of the tailpipes.

Now when I crank it to start it, it literally leaks fuel out of the midpipe at every connection. Something seems to be flooding the engine with fuel.

I bought a new Walbro pump recently but no other changes have been made. I have also had extreme fuel pressure in the tank too.

Running and during priming the pressure would be about 42 psi.

Now, it goes to 42 psi when priming, as soon as the priming is done, the fuel pressure literally falls back to zero in about 1 to 2 seconds.
 
  • Sponsors(?)


silverlx50

Active Member
Apr 4, 2007
122
50
38
Presssure KO is right around 42 only while priming. I havent taken and lines off. Just lriming it four times and testing pressure caused fuel to drip out of the mid pipe
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,894
5,821
193
polk county florida
Check your oil, if it smells like gas don't start the engine. Change the oil ahhh after you resolve the problem.
I would pull the upper intake off then take and test each injector to see which one is stuck open.
 

Mstng93SSP

You have a nice rear end there Dave.
15 Year Member
Nov 29, 1999
2,062
2,393
184
Mililani, Hawaii
Sounds liks an injector stuck full open. You might be able to pull your plugs and figure out which cylinder is full of fuel and that is the injector stuck open. Like carthief said, do not start the engine like this.Change your oil after problem is resolved.

Chris
 
  • Like
Reactions: General karthief

7991LXnSHO

Now I want a 10 year badge
10 Year Member
Sep 1, 2010
3,320
683
174
Kearney, NE
Most people do not mean actually running that much fuel out the exhaust.
check the fuel pressure properly after finding the gusher. Also, no smoking near this car. I hope it did not ruin a cylinder and rings.
 

silverlx50

Active Member
Apr 4, 2007
122
50
38
I pulled the vacuum line from the regulator but it isn't wet and doesn't smell badly of fuel.

Checked oil, It doesn't smell like gas. Most of the car does now but I smelled the dipstick tube but I don't get a strong gas smell, just slightly from the engine bay.

I pulled all the plug and found the drivers side plugs were dry.

Passenger side plugs, #4 soaked with fuel, #3 about half wet, #2 maybe a couple drops and #1 is dry. All 8 plugs look the same other then the fuel.
 
Last edited:

silverlx50

Active Member
Apr 4, 2007
122
50
38
Check your oil, if it smells like gas don't start the engine. Change the oil ahhh after you resolve the problem.
I would pull the upper intake off then take and test each injector to see which one is stuck open.

Could 1 bad injector cause several plugs to be soaked in fuel? #4 plug was soaking wet then as I went forward the fuel decreased until I got to #1 which was dry.

I was hoping the regulator went out, it is 27 years old.
 

silverlx50

Active Member
Apr 4, 2007
122
50
38
I had zero luck testing the injectors. I'm sure I'm not doing something correctly.

When I pulled my upper intake off, I turned it over and a lot of gas came out in the ground, probably a 8" puddle of gas.
 

Dan02gt

10 Year Member
Mar 2, 2003
649
282
113
Greenville, NC
I had zero luck testing the injectors. I'm sure I'm not doing something correctly.

When I pulled my upper intake off, I turned it over and a lot of gas came out in the ground, probably a 8" puddle of gas.
Well there you go. The injectors are in the lower intake. The upper should never see any fuel. Only way for fuel to get in the upper is via the fuel pressure regulator.
 

7991LXnSHO

Now I want a 10 year badge
10 Year Member
Sep 1, 2010
3,320
683
174
Kearney, NE
:banana: Problem found, I hope.
While things are apart, did you do the electrical tests on the injectors? I am thinking about resistance and making sure they click with even a 9v battery, but not near the leaked fuel. It would be a great time for new O rings.

Well there you go. The injectors are in the lower intake. The upper should never see any fuel. Only way for fuel to get in the upper is via the fuel pressure regulator.
 

silverlx50

Active Member
Apr 4, 2007
122
50
38
:banana: Problem found, I hope.
While things are apart, did you do the electrical tests on the injectors? I am thinking about resistance and making sure they click with even a 9v battery, but not near the leaked fuel. It would be a great time for new O rings.

Man I hope so too. I didnt do electrical tests, I dont have what I need to do electrial testing without the risk or short circuit in the pos and neg possibly ruining an injector or more. I need wire and Id like to have some alligator clips. I'm adding them to my toolbox list now lol.

I will be doing new o-rings while they are out and now I've gotta wait for new upper to lower gaskets to arrive so I'll put this thing on hold until probably Friday. Its a good time for me to dump my used oil and buy new oil to put in before I try and crank it up.
 
  • Like
Reactions: General karthief

silverlx50

Active Member
Apr 4, 2007
122
50
38
The car is not back together yet, waiting on lower to upper intake gaskets and injector o-rings from LMR, but I put my new FPR on last night and the car does hold fuel pressure now.

I'm wondering if the FPR was going bad and was causing my extreme tank pressure after doing the Walbro 255 pump as the return line looks great.
 
Last edited:

silverlx50

Active Member
Apr 4, 2007
122
50
38
Changed the oil today. I'd estimate 2 quarts of fuel was mixed in with 7 quarts of oil.
 

Dan02gt

10 Year Member
Mar 2, 2003
649
282
113
Greenville, NC
That’s a lot of fuel delusion. Hopefully your mains are OK.
If you’re getting a lot of pressure in your tank it could be the vent line is blocked or the purge solenoid is not working.
The 255 is a big pump, really to big for the stock lines, and can cause some serious turbulence on the return. If could have also added to the demise of your FPR. If you’re making the kind of power that requires a 255, upgrading your fuel lines and fuel hanger the the ProM one would be useful.
 

silverlx50

Active Member
Apr 4, 2007
122
50
38
That’s a lot of fuel delusion. Hopefully your mains are OK.
If you’re getting a lot of pressure in your tank it could be the vent line is blocked or the purge solenoid is not working.
The 255 is a big pump, really to big for the stock lines, and can cause some serious turbulence on the return. If could have also added to the demise of your FPR. If you’re making the kind of power that requires a 255, upgrading your fuel lines and fuel hanger the the ProM one would be useful.

I hope the mains are okay too. I'm not sure how I will know if they arent...