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Steve Jensen
Steve Jensen, Ford Technician
Category: Ford
Satisfied Customers: 394
Experience:  Ford Senior Master Technician, ASE Master Technician 33 years experience
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1983 ford: 350 motor home 7.5 460 with 26k..slowly..dies..rev

Customer Question

I have a 1983 ford e-350 motorhome 7.5 460 with 26k. Motor starts but only runs 30-45 seconds and slowly dies ,pump the fuel starts up and it runs for another 30-45 seconds. It dosent matter if you idle of rev engine. It would seem something is shuting fuel off.Electric fuel pumps 2-tanks and problem is with both tanks. Good module, and coil, new carb that ran great for a week. This did sit for a while but has fresh gas and all new fuel filters.It just wont run longer than 45 seconds and it will always start to repete problem.Could an ignition module or stator in the duraspark system cause this?
Submitted: 7 years ago.
Category: Ford
Expert:  Steve Jensen replied 7 years ago.

Here is what is most likely happening. The fuel pump relay is engaged during cranking and the carb fills with fuel, the engine starts. When the key is released to the run position, the fuel pump relay is supposed to remain engaged by a different circuit that is connected to an oil pressure switch. If this circuit is not working, then the engine runs until the fuel level in the carburetor drops too low, then stalls. Cranking it again activates the start bypass circuit to the relay and the carb fills with fuel again and so on. I do not have access to a wiring diagram on this vehicle so I am going to have to give you some advice based on memory. Some of these had a fuel pump cutoff unit, but I'm going to have to research that to see if it applies to yours. In the meantime, try this. Remove the interior engine cover. At the top of the block behind the intake manifold, see if there is an oil pressure switch with a three wire connector. Unplug the connector and using a 12 volt test lamp, one wire should be hot with the key on. One wire should flash the test lamp slowly (this is the oil pressure gauge wire). Jumper the hot wire to the wire that is NOT the gauge wire, start the engine and see if it continues to run. If so, replace the oil pressure switch. Let me know if you do not find a three wire oil pressure switch at this location. Do not jumper anything unless it is a three wire unit. Tomorrow, I'll see if I can obtain a diagram appropriate to this 1983 model. Steve

Customer: replied 7 years ago.


Thanks for quick reply. There is a three wire in a harness @ this location with two wires to bottom that clip in and one wire that slides over top of a small spin on canister with exposed threads like a spark plug. I am sure this is it and will try a jumper when I get off work Th. Just in case you have any additional info I will wait for you follow-up on the appropriate diagram to post accept payment. Thanks again I did not know of this service until tonight and I am Impressed with the quick responce and your impressive knowlage of 80's ford.


Expert:  Steve Jensen replied 7 years ago.

Andrew, my apologies for the delay in getting back to you. The cannister device you see is the sending unit for the oil pressure gauge, so let's concentrate on the two wire connector on the other switch. One of the wires should be hot with the key in the "on" position, you'll want to verify this with a test lamp. My diagram shows this to be a blue wire which receives power from the fuse block. The fuse shows to be marked "throt" or "throttle". See if this agrees with what you have. The other wire goes to the fuel pump cutoff unit. If you have power at the switch, go ahead and jumper it to see if it will continue running (as mentioned above). If not, then let me know. I did locate a diagram, but it is unclear as to wire colors at the switch and the fuel cut unit.