350 cummins losing prime

Moline_guy · Jun 11, 2015

If I start this 83 freightliner water truck every day, it starts right up, if it sits a few days it will start and run for a few seconds and then slowly die out and shut down. I then have to give it some either to get it to start and run. I don't see any leaks, any ideas where or why it is losing its prime? Have had the truck for over ten years, just start doing this the past month. Thanks for any information.

Den N Ms · Jun 11, 2015

Moline_guy,It could be a cracked pickup tube in the fuel tank,or a bad fitting or connection,or a holes worn/chafed in the pickup fuel lines between the tank fuel filter or filters and injection pump.Have saw a lot of cracked tank pickup lines inside the tank.To check run a length of plastic fuel line from the filter to in the tank fuel cap hole,prime the filter full and start it up.

roaddevil49 · Jun 12, 2015

If you can get a site glass,put it on the fuel line between the fuel pump and the engine,if there are bubbles, your sucking air, then you will have to find where as stated,check the seal at the tac drive on top of the fuel pump also. To avoid using starting fluid,there is a small pipe plug by the tac drive and the fuel outlet that you can take out to prime the pump, may take several tries but it will start.

tim s · Jun 12, 2015

My Kenworth/N-14 was doing that, I got a check valve at the Cummins shop and installed it in the supply line, there was/is one in the system but I couldn't find it so I added a new one and the solved the problem.

guido · Jun 12, 2015

Hello moline_guy,

Try this: fter the engine starts hit the throttle to the floor. Bet you it will pick the fuel right up. It may pop a bit, but as it picks up R.P.M.'s back out of the throttle. She'll purr like a kitten,

Guido.

Moline_guy · Jun 13, 2015

Thanks for all the information, yes, giving it throttle at starting helps, if it has only sat a day or two, but after that, even giving it throttle it dies off slowly. Truck runs fine after once it is running, so I don't think its a pick up tube, but I will try a check valve first and if that don't fix it I will have to look into that. Thanks again for all the help and information.

Tim in OR · Jun 13, 2015

If it only happens when you have 1/2 a tank of fuel or less, I would start with the pickup tube. Otherwise I would check for a bad line between the tank and pump, or a loose filter.
Tim in OR

350 cummins losing prime

Moline_guy

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Den N Ms

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roaddevil49

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tim s

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guido

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Moline_guy

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Tim in OR

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