Hi,

I've been reading this forum off an on for the past couple of years. Thanks so much for the great resource. I have a '97 GMC 1500 SLE Suburban 4wd with 6.5 Turbo diesel and it has about 165k miles on it. I've run it on mostly B100 biodiesel for the past three years and had the fuel hoses changed once from a leak about a year ago. It started leaking fuel again a few weeks ago so I did some research and bought SAE30r9 fuel injection hose that has a viton lining to prevent the hose rotting I've been experiencing from the biodiesel.

I pulled the upper intake and replaced the following hoses with Dayco GenII SAE30r9 hose:

1. 3/8"ID fuel hose from steel supply line to rear of fuel manager
2. 1/4"ID fuel hose from fuel manager to supply on IP
3. 1/4"ID fuel hose jumper from steel return line to IP
4. 1/4"ID fuel hose from fuel manager to fuel/water drain**** at front of engine.
5. 1/4"ID fuel hose from fuel/water drain**** to open end.

I also replaced the fuel filter and the o'rings on the water sensor and fuel heater on the fuel manager with the correct sized viton o-rings

When I drive the car with a cold engine, it runs fine and doesn't leak. After it gets hot and is running on the highway for about 20 minutes, it runs rough when accelerating from idle up to about 1500-1700 RPM and then smooths out. When I stop and get out with the truck running and look underneatch it is leaking fuel pretty heavily in the center of the vehicle about where the engine and the bellhousing meet.

My question is does anyone know if there is one more soft hose that I'm missing in the fuel system? I'm hoping there is one more somewhere under the lower intake that is rotten from the biodiesel and causing the engine to leak and suck air.

Any advice or ideas you have would be greatly appreciated!

Thank you,

Powell

Sorry, I thought I had already entered a signature on this forum. It should be listed below.

Powell

What about the rubber line from the metal return line tube under the passenger side of the intake manifold to the metal return line running back to the fuel tank?

Chrisk,

Thanks. I knew it felt like I was coming up one line short. Is there a way to see or get to that soft hose without pulling the lower intake? When you pull the fuel manager out, is it possible to see where the soft hose connects to the return line?

I have both GMC Factory service manuals for 1997 and there really isn't a decent fuel flow diagram that shows all of the soft hoses with location. Does anyone have one of those?

Thanks,

Powell

P.S. - I also noticed that we used a 3/8"ID supply hose from the supply hard lines to the fuel manager. It should be 5/16"ID but the one that was on there was 3/8"ID. (it must have been replaced with the wrong size last time around) I'm going to change that out while I'm back in there.

Yes - change that line you mentioned....

IIRC you should be able to replace the return line by just getting the filter housing out of the way...you shouldn't have to pull the whole intake...

Last time I changed my IP feed line I put a piece of "bailer wire" aircraft safety wire to be exact, around the end of hose I was pulling thru so I could use it to be the "snake" for pulling the new hose back under the intake.

That's a good idea. I used good ole' duct tape to attach one end of the new hose to the old hose and pulled it through! :rolleyes:

Of course now that I'm ready to crawl under the hood, severe thunderstorms are threatening.

I'll post when I have it solved!

Thanks,

Powell

Hi Veggie Ranger

do you recall the size of Viton o-rings you used on the fuel manager?

I have a leak there too, appears to be mainly the water sensor, but might as well replace the heater on at the same time.

Thanks

Powell, I'm interested in hearing if you've solved the leak. I have a similar leak which occasionally occurs, right at the bellhousing. Have pulled the fuel filter up out of the way and can't see any fuel leaking...still looking.

I tried to get to the return hose a couple of times and I can't reach the spring clamp on the front to release it. I've got a friend coming tomorrow who's going to help me pull the lower intake so we can get a good look under there to see where the leak is coming from.

I'll post all of the hose sizes and lengths as well as sources and part numbers for the viton o-rings when we're done. (the best source for viton o-rings is www.mcmaster.com)

If all goes well, we'll get the Suburban running w/o fuel leak tomorrow and the diesel engine out of my Ranger and bolted to the bellhousing on the Montero on Saturday. (I live for wrenching weekends!)

Powell

Man, this leak is trying to beat me down! I went through all the lines, tightened up all of the connections. All of the return lines look good with no leaks. I drove it around for a couple of hours yesterday and it worked great.

This morning, we left the church parking lot and the leak was worse than ever once the engine got to temperature. I'm going to pull things apart again and see if I can see the leak. I'm thinking now that the fuel heater itself is leaking and not the o-ring that seals it with the plastic screw-on ring.

On the positive side, this leak only started after running around 3,000 gallons of B100 through the engine over the past couple of years. I just updated to all SAE 30R9 hoses, viton o-rings and new plastic caps for the fuel manager and it's still leaking and appears to be coming from the bottom of the fuel manager.

Instead of replacing the fuel heater, I may buy a Racor 645 and replace the fuel manager with this filter mounted up high on the firewall instead of the fuel manager. It will make it easier to spot leaks.

Anyway, I'll try to post all hose sizes and lengths when I'm done.

Powell

Hmmm... a new fuel heater with o-ring is $140 plus shipping or I can get a complete Racor 645 fuel filter with 10 micron element for $130 plus shipping from Filterboss.

I'm going to pull out the fuel manager and bypass it with a reducing hose coupler to test to make sure that solves the leak. If so, I think I'm going to go with the Racor 645 as a replacement for the fuel manager. Anyone have an opinion on this?

I'm dead set on running B100 in this truck so I'm thinking the Racor with all SAE 30R9 lines will be the way to go. That will also eliminate the third line from the fuel manager to the drain****. I'm in the SE United States where it doesn't get very cold so I can live without the fuel heater for now. I can also see through the filter bowl to look for water and drain it right from there.

For folks in the colder climates who are reading this thread, Racor has an optional fuel heater and WIF sensor for the Racor 645 according to the specifications. They could probably be wired into the harness with a schematic as reference.

Powell
www.southerngrease.com

I bypassed the fuel manager with a 3/8"ID to 1/4"ID reducing coupler from McMaster-Carr

44555 K188 Brass Double-Barbed Vacuum Tube Fitting Reducing Coupling for 3/8" X 1/4" Tube ID

I tied a rag around the coupling and drove it around for 30 minutes. The leak is still there but not at the coupling.

So now I have eliminated the fuel manager as the source of the leak. Back to chasing the ghost!

Powell

Have you looked at your injector jumper return lines as a possibility

Hmmm... a new fuel heater with o-ring is $140 plus shipping or I can get a complete Racor 645 fuel filter with 10 micron element for $130 plus shipping from Filterboss.

I'm going to pull out the fuel manager and bypass it with a reducing hose coupler to test to make sure that solves the leak. If so, I think I'm going to go with the Racor 645 as a replacement for the fuel manager. Anyone have an opinion on this?

I'm dead set on running B100 in this truck so I'm thinking the Racor with all SAE 30R9 lines will be the way to go. That will also eliminate the third line from the fuel manager to the drain****. I'm in the SE United States where it doesn't get very cold so I can live without the fuel heater for now. I can also see through the filter bowl to look for water and drain it right from there.

For folks in the colder climates who are reading this thread, Racor has an optional fuel heater and WIF sensor for the Racor 645 according to the specifications. They could probably be wired into the harness with a schematic as reference.

Powell
www.southerngrease.com (http://www.southerngrease.com)

I live in the SE U.S. as well , in West Texas to be exact, I installed a Racor Fuel filter in my truck last year thinking it would be fine b/c it doesn't get that cold and this past winter the fuel in my racor filter and filter bowl became jello and I was stuck in a parking lot in Lubbock, TX trying to get it fixed to so I can get 10 more miles back to my house. I was running B50.......I eneded up towing it home dropping the tank, cleaning it out, putting a new racor filter and new stock filter on and buying a heated bowl. Since then I run a heated bowl and when winter hits or I am going to colder climate I use and anti-gel additive in every tank.


Do you make your own B100 or do you buy it? I have been buying most of mine and switching to making my own.

I have the Suburban jacked up with the passenger front tire off and I'm trying to remove the wheel housing to get to the return jumper hoses on the passenger side. I've removed all of the bolts and nuts and the housing is moving freely in the wheel well. However, I can't seem to get it out! Does anyone know which trim pieces need to come off to get the housing out? I'm hoping to have a clear view of the passenger side of the engine so I can crank the truck and see where the leak is coming from.

Thanks,

VR

Well, I gave up and took the truck to a diesel shop I trust. The leak was not biodiesel related and was coming from a kinked hard line to injector #4 up under the turbo and manifold! He had to pull the top end to replace it. He also fixed a few small coolant leaks while he was in there.

The good news is that the truck isn't leaking anymore. The better news is that I now have all viton lined fuel hoses in my fuel system that will hopefully last a long time!

I saved all of the old hoses and will do a writeup soon and post a link here so others with this problem will have hose sizes, lengths, o-ring part numbers, etc.

Thanks for all who tried to help with this!

VR