Problem on my Winnebago, 6.5 L65. Potential fuel leak back and bad battery?

[benh84]

So, I am based in the UK where I own an imported 97 Winnebago Brave. It was parked up a long time until recently, when I got her running again and everything seemed good.

I had done a full oil and filter service last year as well as replaced the lift pump, and since then had driven around 500 miles. I put a small amount of questionable diesel into the vehicle after a long journey to top the tank up, maybe 40l on top of the 200l of good diesel. As soon as I realised, I stuck some biocide into the tank as a precaution.

Quite literally all on the same day, returning from the long trip, topping up diesel, the vehicle began cutting out and struggling to start. I pulled the fuel filter which was a brown/red color and there was a lot of sediment sitting in the filter manager housing. Looked like rust and filings, I'm assuming from the tank internals, I cleaned the filter housing out and put in a new filter, primed the system and could not get the vehicle to start.

There were a couple of factors, I think there was a good amount of air stuck in the ds4 pump and lines, but also my battery system had been previously modified to only take one large battery, (which I think is on it's way out.) The volage was sagging below 10.2v when cranking. I eventually managed to get it going, by cracking the majority of the injectors and putting a huge boost pack on the battery to give it an extra kick. Eventually she started, loads of grey/white smoke, but ran beautifully again, without cutting out whilst driving.

A few days later, I tried to start again, and it was a struggle. Felt like before, lacking any fuel or air in the system and then eventually it goes, white smoke. I removed the fuel filter again, checked the o ring and replaced it, made sure it was tightened down and bled it through, started much easier this time.

Next time I went back to start it a week later, struggled again.

Now the starting is poor every time I turn off the vehicle, even 1 minute after struggles to restart. When it does start, i usually have to put the boost pack on and crank a lot more and the smoke is dark grey now, I'm assuming as more fuel is collecting and then being burnt.

I did a bit of research and I may have knocked one of the fuel return lines when cracking off the injectors, is this a common place for air to get in and leak back? There is no sign of a diesel leak, I want to get some fuel line to replace these, this weekend, what internal diameter pipe is needed for this? I've seen people just pushing pipe on and others using clamps, what is the correct method? I don't think I've disturbed anything else and it ran and started great before.

I have also just ordered 2 x 12v 95ah 850cca batteries to go back to a better setup, as I think the existing battery and the now colder weather is also impacting the vehicle starting. I'm hoping by fitting these first I can rule out that being part of my starting problem.

This weekend, i'm going to fit the batteries and try to replace the fuel return lines and drain the fuel tank, refill it with fresh fuel.

Is there anything else anyone can suggest? or where else I should look?

Appreciate any advice, knowledge on these engines and vehicles in the UK is limited. Thanks.

Ben.

 

[JayTheCPA]

Given the symptom of cleaning out the fuel filter, engine runs fine for a while, and looping back to cleaning out the fuel filter once the engine no longer runs fine again, my vote is to drop the fuel tank and check for whether it still has crud. Once confident that the tank is clean, we can then troubleshoot (if necessary) from that point.

By the way, if the fuel system does not have a pre-filter (outside of the tank, and upstream from the main filter), now is a good time to install a unit. Related, if the tank's pickup line happens to have a pre-filter (commonly known as a sock here in the Colonies) inside the tank, now is also a good time to get rid of that thing as it is known to clog and cause problems.

 

[Will L.]

Ben, normally GM says begin with replacing the 1/4” diameter fuel line that comes out of the front of the ds4 with clear tubing. It is about 6” long in an upside down U shape. You want clear tubing in this location. If you get pvc tubing, it will last about 3-4 years and need replacing. Fuel-line.com sells it as rated fuel line and from current testing on it- it will last many years. With the clear line in place- monitor it for air intrusion by seeing bubbles flowing through- also you can see contaminated fuel.

As for the return line that goes from injector to injector it is 1/8” diameter.
Yes they can allow air problems. All the return lines from ds4 & injectors connect together and go back to the fuel tank where the line always stays submerged at the bottom of the tank to eliminate the issue. But they will usually have a visible leak of fuel when they fail, unlike the supply side of the fuel lines.

Leroydiesel.com sells the kit to replace them. Or get some Mercedes Benz for the OM617. Do get it at a Mercedes dealership, not the cheaper stuff, because there is a world of difference in quality. It goes on without clamp. You have to fight to get it off, usually cut it is easier. It is sold from a roll, not precut lengths. I suggest making the loops slightly longer than GM did so that you can cut it once and reuse if needed on the injector.


You sound like you identified the problem. We know fuel is expensive- but free fuel is to expensive to keep when bad as it can cost you a new ds4, injectors, and maybe more. Get that fuel tank out and cleaned NOW.
Use a small fuel container hooked to the lines while the tank is out. Disconnect the fuel line from the ds4 and into a container. Pump 2 liters of gasoline (petrol) through the lines. Then 1 liter of diesel fuel. Now replace the fuel filter.

You’ve a choice to make. Save the bad fuel and haul it to where you bought it to see if they will pay for replacing the fuel along with associated costs, or dump it.

A suggestion while you’re going through all this: replace the 30 year old rubber fuel line portions while you are at it to avoid what should be happening in the next 5 years of failure (and possibly could be contributing to it now). In the USA I would tell you to be 100% sure the new fuel line is SAE30R9. This is the wear resistance outer line that can withstand Ethanol, Methanol, gasoline & diesel fuel. The reason is since the fuel was altered for better emissions from high sulfur diesel to ULSD and the addition of the alcohol to it for cleaner emissions,- the new fuel deteriorates the fuel line from the inside out. And the fuel line will look perfectly good while chocking the actual fuel supply, plugging the filter or simply stopping flow because it makes a flap inside the hose like a valve.
More of the clear tubing could be used here- but does not have the abrasion resistance. With an rv, your areas might allow for it. The pvc clear is not rated for the alcohols, uv light, etc. but the stuff from fuel-line.com is. In pickups they use 3/8” line from tank to fuel filter, then 5/16 from fuel filter to ds4. Ideally owners modify and enlarge it to 3/8 line everywhere (search Feed The Beast or FTB).

And while I am in there spending all your money and labor…
Lift pump, filtering, pressure gauge…
Get a metal T fitting at the ds4 that is after all the rubber line to add a fuel pressure sensor. Mount the gauge in/on the dash where you see it while driving. Anything below 1 psi at any time is amazingly destructive. The desired range is 8-14psi the factory lift pumps used in most pickups and hummers was inadequate. It made them run but proper pressure improves performance and in a some cases improved fuel efficiency. The added fuel flow definitely improves ds4 lifespan.
The liftpumps are “flow on fail” so the engine continues to run while ruining the ds4 and often the driver has no clue. Low dollar trucks makes it hard to justify, but a more valuable vehicle, especially one that is more expensive to have worked on- makes this a no brainer decision:
Fass lift pumps with the Fass filters attached. If you need a fuel heater for your area, add their fuel heater to it. Completely eliminate the factory lift pump and factory fuel filter system. The fass will flow better, polishing your fuel while running to much, much cleaner levels. Their water filter separation is unmatched. While the factory unit can only stop a couple of Tablespoons of water before it bypasses the water to the ds4 and can ruin it - the fass will hold over a liter of water then eventually stop flow. It will not allow any water to make it to the engine.
If you keep the original lift pump, strongly consider adding the Fass filter to your system as a stand alone filter before the FFM.

Some folks mount a mechanical fuel pressure gauge at the Fass lift pump and skip the dash mounted gauge- it eliminates diagnostic while driving- but is better than no gauge at all.

If by chance- your rv has a mechanical lift pump that is mounted to the engine on the right foreward side of the engine - know that GM stopped using them due to failures that flood the oil crankcase with diesel fuel and ruin the engine. Bypass it and go to an electric lift pump asap. It is best to remove the pump and the push rod (which will just slide out) then replace the pump with a block off plate. If you have this, speak up and we can show you what the blockoff plate is. If you just bypass it and not remove it- plug the fuel inlet & outlet ports as they become a dirt contamination point to the crankcase and eventually an oil leaking point.

 

[JayTheCPA]

FWIW, there is an aftermarket kit for older Dodge diesel trucks which is a simple light and sending unit to indicate when the fuel line psi gets low (IIRC, 4 psi and less) which is also perfect for the 6.5 diesel. So, if looking to add a pressure gauge visible at the dashboard, will not hurt to take the extra steps to install the warning light while working in the same areas.