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Help! Towed back to shop


EWB555

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1995 RD688S E7-400. Shut off today, while driving. Seems to be a fuel problem as it will start and run on either. All accessories are coming on when turning key so ecm should be getting power. Thoughts on what to start with to trouble shoot? This engine is computer control but not an etec. Appreciate any suggestions!

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I'd check to see if the fuel pick up tube in the tank may have cracked or broken off. Also the ECU is very sensitive to voltage drop. Anything below 11.5 volts and it has running issues, its more of a problem on those as the cab and chassis electrics are 24v and the engine is 12 volt. Check to see if you have a battery on the way out.

 

"OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK"  Thomas Edison

 “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’

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Ok, so this evening I checked every single fuse, circuit breaker and relay, all good. No malfunction light on. Voltage was 12.5 in the fuse panel. Turned key on  and had 12+ on on one pin at the round fuel  pump connector, and an even 3 volts on another. Looked in both tanks, pickup tubes seem in tact, cracked fuel line at the pump and there is fuel. Thinking it has to be something with ecm or pump electronics. When cranking it doesn’t even try to start, shoot it with either and it will run a few seconds. Not sure where to go from here, appreciate any suggestions. 

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We have had an eecm take a crap on us out of the blue on 1 of our cat motors.  The truck was running great, shut it off on a job site and it would not start.  Spent 2 days trying everything under the sun to no avail.  Finally got an eecm out of a wrecked truck and it fired right up.

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I use to have a steel fuel line I’d hook to the pump with a tester jig and injector. Kinda like those spark testers used on you lawnmower engine only for diesel. Gives you a quick answer on delivery. Put your cigarette out though. Crack a line and see what’s pumping out one of the six top delivery ports. Stick a fuel pressure gauge in-line after fuel transfer pump. 

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Well, we know it's not the fuel transfer pump. Dad talked to a mechanic who suggested we try that, he picked one up and put it on today, nothing changed. I am going to mess with it Sunday, it's going to rain here all day Saturday. We didn't want to put the truck in our shop since it's loaded. Will definitely crack one of 6 lines on the pump and see what we have.

From there I'm going to start checking wires in the harness. Does anyone know how to check the sensor in the side of the pump or the one in the flywheel housing? Will these make it not run if they fail?

I have a multimeter and can check voltage, resistance etc. Just not sure what I need to look for.

I do appreciate everyone who has chimed in with suggestions!

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