Diesel fuel smell

Topic: Diesel fuel smell (Read 1056 times) previous topic - next topic

Diesel fuel smell

June 06, 2019, 08:04:18 am

Lately I've noticed the smell of diesel fuel inside the coach. Only happens when climbing grades at full throttle. No sign of leakage that I can find. I've opened all outside compartments and can see or smell nothing except at the passenger side fuel tank, where there is some diesel odor.

What's going on?

Is it possible the return fuel is splashing or foaming and getting out the filler neck or cap? The tank is near full.

Re: Diesel fuel smell

Reply #1 – June 06, 2019, 09:31:26 am

First suspect is Fuel cap .. then fuel line and aqua hot(if you have one). Generator fuel filter.. there are 2 and one is under the coach at the passengers seat almost towards the middle. Generator fuel lines?

Re: Diesel fuel smell

Reply #2 – June 06, 2019, 09:33:44 am

Somewhere, somehow any tank has to be vented. Might start your search for solutions there. Hot diesel returning is more likely to evaporate.

Re: Diesel fuel smell

Reply #3 – June 06, 2019, 11:09:01 am

Since the smell appears to be around the filler, I switched caps side to side last night . I might also rubber band s baggie over the cap as a test. Both caps are equally old, but look ok.

The rubber bellows around the neck is long gone, but appeared to be cosmetic only.

I'm going to try some sealing tape around the neck. Then see if it's any different on Saturday, my next driving day.

Would a new cap be a common auto-parts item? I have a Walmart nearby.

Re: Diesel fuel smell

Reply #4 – June 06, 2019, 02:51:45 pm

Don't know about your coach but our fuel cap is a pressure cap holding a couple of pounds pressure while running and gives a puff when we fuel. A little diesel can really smell. Not as bad as a gasoline leak thought. Take a look at any part number that may be on the cap and then look up the specs for the cap.

P

Re: Diesel fuel smell

Reply #5 – June 06, 2019, 03:00:11 pm

Quote from: Old phart phred – June 06, 2019, 09:33:44 am

Somewhere, somehow any tank has to be vented. Might start your search for solutions there. Hot diesel returning is more likely to evaporate.

My FT has a separate vent hose coming out the top of the tank and exiting beneath the compartment floor.

Re: Diesel fuel smell

Reply #6 – June 06, 2019, 05:16:36 pm

My 03 also has a fuel vent line also. Would think Tom's would also.

Re: Diesel fuel smell

Reply #7 – June 06, 2019, 05:19:41 pm

Good observations so far.

DO put finding the source and correcting it high on your "to do" list. Diesel fuel smell is hard to get rid of AND, if it gets down into the foam insulation in the basement floor, it will DISSOLVE IT. I have seen that (wavy bottom FG) on a couple of coaches I have inspected.

Re: Diesel fuel smell

Reply #8 – June 06, 2019, 06:02:13 pm

Quote from: Tom Lang – June 06, 2019, 11:09:01 am

The rubber bellows around the neck is long gone, but appeared to be cosmetic only.

It's a CV-joint boot, IIRC.

Re: Diesel fuel smell

Reply #9 – June 06, 2019, 07:14:26 pm

My cap is un-vented. I bought two new ones today.

Yes, the bellows was a cut cv joint bellows. I never bothered to replace them.

I plan to seal around the filler neck with self fusing tape.

Back on the road on Saturday. Will see if it has improved.

No Aquahot, but for all 11 years I've owned it, there has always been a slight diesel smell in the bays.

Re: Diesel fuel smell

Reply #10 – June 06, 2019, 08:34:32 pm

While changing out the fuel caps and adding the tape, I noticed a definite diesel trail running from the filler down the face of the tank to the drain slot.

I feel good that I may have it solved

Thanks all. I'll report back on Saturday.

Re: Diesel fuel smell

Reply #11 – June 08, 2019, 11:57:08 pm

Maybe better, but not resolved.

No diesel smell in any of the outside compartments other than a tiny bit around the passenger side filler. Might be residual spillage.

But I still get the diesel smell inside the coach while on the road. Possibly more when driving hard uphill. And it appears to be everywhere, but not around the engine or generator

And no signs of leaks.

Is it possible the return line is leaking fumes but not liquid diesel?

Re: Diesel fuel smell

Reply #12 – June 09, 2019, 12:06:09 am

Not very likely fumes are in the return lines. A little bit of diesel liquid will leave a lot of odor.

Re: Diesel fuel smell

Reply #13 – June 09, 2019, 01:15:25 am

You got it. Vented and use original gunk underneath the entire front end then rinse it off.

Drove me expensive crazy long ago.

Stream of fuel after a hard long grade pull without vented caps. Duh.

Posted this long ago.

Re: Diesel fuel smell

Reply #14 – June 09, 2019, 01:20:22 am

My caps are not vented, but the tank should be.

Re: Diesel fuel smell

Reply #15 – June 09, 2019, 01:25:43 am

Now find air/odor/ water Vapor leaks into the coach and seal them up

Re: Diesel fuel smell

Reply #16 – June 09, 2019, 01:36:34 am

The tank is vented, full tank. Big hill. Non vented caps. Big stream of fuel under front of coach.

Re: Diesel fuel smell

Reply #17 – June 09, 2019, 07:22:39 am

Quote from: Caflashbob – June 09, 2019, 01:36:34 am

The tank is vented, full tank. Big hill. Non vented caps. Big stream of fuel under front of coach.

If this is the case then the vent line check valve is bad and needs replacing.

Mike

Re: Diesel fuel smell

Reply #18 – June 09, 2019, 09:23:03 pm

The fuel line, which is under vacuum while driving, will release diesel fumes through tiny cracks when you're parked. How old are the fuel lines? I had diesel smell from small spills while refilling. FT removed the tank covers and recaulked all floor penetrations. No more smells.

Re: Diesel fuel smell

Reply #19 – June 09, 2019, 09:43:43 pm

My fuel lines are original, from 2003. My mechanics looked them over a few months ago and said they were still good.

Re: Diesel fuel smell

Reply #20 – June 09, 2019, 10:20:41 pm

Apparently not?

Re: Diesel fuel smell

Reply #21 – June 13, 2019, 07:07:11 pm

Good news. Problem solved.

It was a nothingburger.

Last time my mechanic worked on the engine, he lowered the bed onto the control box for my electric mattress pad. Left about a half inch gap for exhaust gases to get in.

Drove five hours today without a hint of diesel fumes.

Re: Diesel fuel smell

Reply #22 – June 13, 2019, 07:38:28 pm

Don't you love free fixes?

Re: Diesel fuel smell

Reply #23 – June 13, 2019, 07:46:29 pm

Tom ---- You may have a diesel leak around your engine some where. I'd check under the injector pump seal. I wouldn't think that you'd smell diesel if there wasn't a leak some where. Could be a loose injector or connection. With the engine hatch not sealed, I could understand an exhaust smell, but not a diesel smell unless ----- Have a great day ---- Fritz

Re: Diesel fuel smell

Reply #24 – June 13, 2019, 08:46:36 pm

I cleaned up the spillage around the tank, and no longer smell diesel anywhere. I suspect it was exhaust. May be a little unturned diesel in the exhaust under certain full throttle conditions.

Affiliate Notice