wetcamp

Hi 1986 E-350 motorhome that will run if I give it gas in the carb but won't pump any to it. I have checked the inertia switch and it has power going to it as well as the tank selector valve that is mounted on the frame. The posts there change power there when you change the toggle switch at the dash. It has 2-tanks an both will not pump gas. I also have power at that same valve for the fuel(blinking) guage, but it does not work either as well as the water temp, oil, amp guages on the dash. Have checked for power behind the intstrument panel with test light, and it will blink at all that guages, and if held long enough they will also work as well. Fuse box test good on both sides of fuse's except on the lower right hand corner one which has no power at all. Could all this problem be because of a lack of ground? If so where would that problem be? It starts, it has headlights, wiper works, but heater fan does not, although I have removed that and connected it direct to battery and it works fine. Please help driving me nuts!!

 

thefonz

You said the inertia switch has power coming to it, does it have power going out? Can you hear the fuel pump run? Have you checked fuel pump relay? Check grounds, engine to frame or body and body to ground. There may also be a small ground wire coming off the neg battery terminal. Make sure that is good. Have you checked fusible links?

wetcamp

yes I have checked all the fusible links and they have power on both sides. I also have power on both wire's coming out of the inertia switch. I have not checked for grounds yet, but remeber starter turns the engine over and I have headliights as well as windsheild wiper's. No you do not hear any fuel pumps working in the tanks. If it would be a ground where do you look for the chasis ground? There seems to be power in alot of places. When I checked the switch valve for the tanks I unplugged it and checked those terminals with a test light and grounded to the frame so shouldn't the ground be ok? Thanks for the reply.

thefonz

Your grounds may be ok. Since you can't hear the fuel pump come on, check for power to the pump. If it is not getting to the fuel pump, check the fuel pump relay. If it is getting power to the pump... your pump may be shot. Verify before replacing. Good luck.

Mbrgr1

Hello, I feel your pain, I have a 1988 E250 based motorhome, and just got done getting my fuel system to work, and in the process, believe I have a pretty good understanding of that system. Each tank has it's own low pressure pump that not only delivers fuel to the high pressure pump, but is also responsible for switching the "dual mode selector vale" so that the fuel is taken from the correct tank, and return fuel is delivered to the same tank, something they are famous for not doing all the time. On the electrical side, the fuel pump relay sends power through the tank selector switch to the correct tank, the tank selector switch also switches the signal from the sending unit in the tank to the fuel gauge on the dash. the sending unit signal can be identified by a pulse indicated on a test light or vom. The connector on the rear tank is easiest to get to, I had someone turn the key on while I measured voltage at the connector. There are 4 wires, two for the sending unit, and two for the pump, again, the signal from the fuel gauge will pulse with the key on constantly, and the + signal for the pump will be constant on your test light or vom. if you have that signal and a good ground (one of the wires at the connector) your pump should run. Two of the wires on the connector will be grounds (you'll need to conect your test light to 12v +) and two are hot, one pulsed for fuel gauge, and one constant hot for the pump, until fuel pressure is achieved and the fuel pump relay shuts it off, which in your case is not happening. Mark