M35 fuel bleedback problem.

[truckfest]

Having problem with m35, after sitting several hours or more ,fuel bleeds back to tank. Truck will struggle to start , running fuel pump for 15 seconds helps greatly but Truck still stumbles a while. Is there a check valve I can't find or is it in the pump?Thanks for any thoughts

 

[gimpyrobb]

Bleed back to the tank would indicate maybe a fuel filter seal not seated properly, an injector line loose maybe, or deteriorated fuel line. Try checking gaskets first, the tightneing up your fittings. Let us know what happens.

 

[Boatcarpenter]

How do you know that it is bleeding back to the tank? How did you check that? If in fact you know for sure that it is bleeding back to the tank, then I would check for leaks. If you don't know that for sure, then you have some other possibilities. Plugged filters, in tank pump has possibly come apart as several have had happen and may not be pumping very well if at all.
You really need to get a good handle on the problem to get good helpful answers.
BC

 

[truckfest]

Thanks to all! Problem fixed,started with fuel filters .Primary fuel filter housing gasket was mostly "inside" the housing no idea how this did not leak.Changed secondary filters as well, next day still poor start! Went to checking every fitting (there was no leakage at any time) ,vent and "by -pass "on top of secondary filter housing were both not very tight, next day . Went to "check valve/disk "? on bottom of inj. pump ,hard to get to,next day Finally I went to the flexible line from primary filter to bottom of inj. pump.This line has "Push Loc"? fittings I put two ss clamps on this line,net day. Thanks again!!!
I have been trying to find secondary fuel filters that have the correct gaskets.Wix 33540 and Luber Finer L540F filters fit but gaskets do not.

 

[cranetruck]

.......... Finally I went to the flexible line from primary filter to bottom of inj. pump.This line has "Push Loc"? fittings I put two ss clamps on this line,net day.......

Makes me wonder about those Push-on type fittings, OPCON reported a problem with them last year on his trip and lost a lot of oil.
My 8x8 uses a lot of them and although I haven't had any problem, I'm now inclined to go over them with hose clamps....