Not sure where else to post this so ill just start here. So we were in the middle of Minesota today enjoying a great mixed CD and some decent weather when out of no where i lost gas flow from my rear tank and had to pull over. Basically, i have two tanks with an aftermarket fuel system, i dont know anything about how its supposed to be set up but mine has two tanks with two seperate electric fuel pumps, each has an inline filter and both go to one junction box which is controlled by a switch to swith between tanks. The front tank is running just fine and i can drive for miles on it, but when i switch to the rear tank it will run for a while and then cut out. Its a pretty strange problem because the pump is actually still running as does the van but only for a while, and if i change over to the front pump for a moment then switch back to the rear it will run for an even shorter period before cutting out. Another strange fact, it runs for a good deal of time idling on ther rear tank, it runs for prolly 10 minutes idling before cutting out, but it doesnt just stop, it kinda tapers down to a sputter before stalling. So im not sure what else to say, i pretty much have the prob isolated all the way back from that block that swithces tanks, and the only things it could be are the actual lines, pump or tank, but i just dont know what to say becasue the pump is still pushing gas. Is there any chance its not pumping with enough pressure? some mechanic said since it was a Carburated vehicle that it really doesnt need much pressure. Anyways im going to do a flow test tomorrow morning but i could really use some help, sorry for the novel here but im just trying to give all the info i think might help, hope aone is well otherwise, thanks agin!
Fuel supply issue? Please Help
- Thread starter Tress
- Start date
Martyn
Supporting Sponsor, Overland Certified OC0018
If your electric pump checks out OK, I'd say you have an obstruction in the fuel line between the tank and the common switch box.
The reason I think this is you can idle for some time before it cuts, the fuel is flowing just not fast very fast, but because it's at idle the bowl in the carb is staying full.
As more fuel is needed during driving the pump can't keep up due to the obstruction the bowl empties and the engine stalls.
The reason I think this is you can idle for some time before it cuts, the fuel is flowing just not fast very fast, but because it's at idle the bowl in the carb is staying full.
As more fuel is needed during driving the pump can't keep up due to the obstruction the bowl empties and the engine stalls.
ntsqd
Heretic Car Camper
This sounds like the classic case of debris in the fuel tank. Aftermarket tanks are particularly prone to this failure mode. At low flows the sock (coarse fuel filter on the end of the pick-up) in the tank can pass enough fuel to support idling and usually not much more. At higher fuel volume demands the debris clogs the filter. It doesn't imbed in the filter, just sticks to the outside like a wet maple leaf. Remove the demand and the 'leaf' floats away. Resume the demand and the 'leaf' comes back.
Another possibility, along the lines of Martyn's suspicions, is that fuel hose can delaminate and create flaps inside the hose. At low demand these constrict, but don't block the fuel flow. At higher demands they can totally shut off the flow of fuel.
I would start with inspecting all of the hoses. Replace any that are exceptionally hard or soft.
Another possibility, along the lines of Martyn's suspicions, is that fuel hose can delaminate and create flaps inside the hose. At low demand these constrict, but don't block the fuel flow. At higher demands they can totally shut off the flow of fuel.
I would start with inspecting all of the hoses. Replace any that are exceptionally hard or soft.
ntsqd said:
The lines for the rear tank run on the inside of the frame rail so im sure they are old cuz they are so hard to get to, so once we run a flow test hopefully that will tell us something. As for the tanks though, how do you get debris out of a gas tank? I assume i would have to drop the tank? But then what LOL! Man i hope its the pump or the hoses!! Thanks aone for the help!!
You have classic symptoms of a plugged tank vent. With a plugged vent, the supply pump is pulling against a vacuum and after a while the vacuum increases enough that no more fuel will flow. Find the vent and confirm it is clear before pursuing other diagnostic paths. Often times the vent is in a location that can allow dirt to plug it up or an insect might crawl in there etc.
You can usually confirm it is a vent problem by running the vehicle on the problem tank until it stalls and then open the fuel cap. If you can hear air rush in, it shows the vent is plugged. You could also test the hypothesis by driving with the fuel cap removed or loose enough to let air in. If it runs fine that way, the vent is plugged.
You can usually confirm it is a vent problem by running the vehicle on the problem tank until it stalls and then open the fuel cap. If you can hear air rush in, it shows the vent is plugged. You could also test the hypothesis by driving with the fuel cap removed or loose enough to let air in. If it runs fine that way, the vent is plugged.
Well for now i think its the pump, first thing this morning we did a flow test after where both tanks combine and the front pumped fine and the rear nothing, well i went to the rear pump and jiggled the wires going into it and it started right up and started moving gas agin. So after a few times of going from front tank to rear and moving each wire seperately i pretty much pinned it down to a bad connection inside the pump. Either way thanks for the help and sorry for the confusion, i swear the pump was running when i checked it yesterday! And who knows the bad connection may have only been part of the problem, we shall see!
Pad
Adventurer
Tress said:
Glad to here you're not stranded! Thats the worst!
Those dual tanks are a headache waiting to happen, if you ask me, my GF had a 80's van w/duals and eventually I told her to only use the tank that was always problem free.
I'm in the twin cities, about 4 hrs east of there.
Sounds like youve got the issues figured out, fingers crossed.
Which way are you headed/going too? Where are you coming from?
This sinerio reminds me of a motorcycle 'black book' I heard about a years ago where it listed people and #'s in different states that could help a fellow biker out if they had trouble.
Wonder how a 'need help now- in route' section would go over.
Anyways hope youre plans arent too spoiled with running only one tank.
Pad
Well if the new pump resolves the issue we'll be back on the road and on with the journey. I am coming from VA and headed toward AK so our plans wont bring us back through the twin city unless need be, but i love your idea about the need help thread. Either way we are picking up the new fuel pump in the morning and will install it right away so keep your fingers crossed for me, and thanks aone, we'll be around here often and ill post my website asap so you can all see what we have done, and im sure you'll have plenty of pointers. Until nex time, enjoy the ride!