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H3-40 losing fuel
I have a 1991 H3-40 VIP that we have owned 3 weeks. Drove it 700 miles home with no problems and started everytime on half a turn. A couple of days after getting home ti did not want to crank from the front, so I went ot the back to see what was going on. If I held the start button it spin faster and faster till it started. Did this twice over the period of a week. This Friday it Started and ran for 30 seconds and shut off. Checked the filters and the Racor and the secondary were out of fuel. Filled them both and the engine started and ran fine. Shut it down and within a few minutes the filters were empty again. Refilled them and started and drove 25 miles and filled that tank just to be sure the guage was working. Only took 130 gallons to fill a 235 gallon tank, so that eliminated that issue. Came home and shut down the engine and turned off the cuttoff feeding the Racor filter. Last time I checked the Racor was still full. I am leaning toward a bad check valve.
How much fuel is supposed to be in the Racor? Is it supposed to be full to the top? That seemed to get it started. I have ordered a service manual from Prevost but it has not arrived yet, so where it the check valve on the H3-40? I also checked the oil and it is not making oil so hopefully I do not have a fuel leak at the injectors.
Thanks,
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17 Replies
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Tom, When I change my fuel filters I reprime them by filling them. In the case of the Racor I fill it to the very top after installing the pleated element, but the next time I change filters it is likely to be down a little. I think your Racor may be high mounted in the center of the engine just behind the door. A bad check valve will allow that to drain back into the tank since it is probably above the fuel level in the tank. My Racor is mounted low along side of the engine so it may be less likely to drain back into the tank.
I presume no fuel is on the ground.
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Hi Jon, Thanks for the reply. I have not seen any fuel underneath and my filter is located beside the 8V92 about as low as it can get. It is located in the passenger side rear door.
Thanks,
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Then you have reached the end of my limited brain power because by mounting low I would not think fuel would drain from the Racor to a level lower than that of the fuel tank. What you suggest says the Racor is mounted way lower than what would likely be your fuel level.
The only thing I would think would cause fuel to come back out of the Racor or other fuel filters would be if your fuel tanks vent(s0 were plugged and you had a vacuum in the system sucking fuek back into the tank. You don’t hear a hiss when you open the fuel cap do you?
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Jon,
I will check that as well.
Thanks,
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Easy to check. Go for a short ride, and as soon as you stop open the fuel cap. No vacuum then
And if you still lose prime at least that is ruled out.
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Even if the Racor is mounted low, a bad check valve would bleed off the pressure.
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Had my racor rebuilt at Jax Prevost. Stellar job, broke a housing bolt, had to rethread , etc. Should have just bought the newer model Racor, would have been cheaper. Could try using the manual shut off valve (mine has one) just forward of the racor ?
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Taking the bus age into account after reading your post my first thinking was fuel line. If the line is bad the pump sucks air and min. fuel. Cracks where the line flexes and ply seperation near the fittings are common causes.
The fuel vent at the tank is another good probable cause for problem you have. After you fueled and making sure the cap was tight might of just sealed the system.
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Thanks for all the replies. I was looking at my parts manual last night, (my service manual has not arrived yet) I noticed the check valve is on the return line to the tank. That did not make sense to me. On my Eagle it was on the feed to the filter. Is that right? Or is the parts manual wrong?
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Tom, the check valve is by the tag axle on the supply line mine was I moved mine to primary filter, check also some had a pickup pump close to the fuel tank is your tank plastic or stainless plactic tanks used a different setup
good luck
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Hey Clifford,
I am not sure about the tank, it is hidden behind the stainless walls in the coach AC/Heat bays. There is an access panel in there though and I can check. I did find a book on the Racor filter last night and it shows that there is a check valve in the the filter canister itself that should stop it from leaking back in to the tank. I suppose it could be bad so that is one more thing to check out. I love a challenge!
Thanks,
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Tom, as I mentioned in my earlier post, Prevost Jacksonville easily and quickly diagnosed by Racor check valve problem, mentioning that it was an often found problem. I had had some funky fuel problems just prior to this, so it seemed to bear them out. I have not had a problem since in over 2 years (related to fuel that is.)
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Thanks Rodger,
I will repair the check valve in the Racor first. that does seem the most logical.
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Tom, we almost bought a Hoffman Conversion, have seen several and even went to PA to visit and see their operation. Don was a consumate gentleman (and salesperson) sadly missed. Great coach work. Love to see pics
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Rodger, I will try to post some when I get a minute.
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