Starting problem 400 Engine.
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Tuned
Joined: Apr 2013
Posts: 498
Likes: 53
From: Sweden
Starting problem 400 Engine.
Hi! I would appreciate some help from you guys. Started my Truck for the first time in 3 weeks today. Had to crank it a lot to get it started. If I am going to start it tomorrow it would start right up, both cold and warm. Feels like a fuel problem and not an ignition problem. It has a mecanical Fuel Pump. Are the Fuel Pump suppose to "hold" the gas from not running back to the Fuel Tank?
Lead Driver
Joined: Jul 2017
Posts: 9,545
Likes: 1,156
From: San Jose, CA
They can hold the fuel back, but don't always. Probably depends on what position the pump is in when the engine stops.
Do you have an open element air cleaner? That might allow fuel to evaporate quicker out of the float bowl.
Might also be the float level is now lower, meaning less gas to evaporate before empty.
Also might be draining back out of the line due to an older, weaker pump.
Do you drive it much? How old is the pump? How long has it sat since it was replaced? A fuel pump that is not used much is way more likely to fail early than one that gets used regularly.
Especially with today's fuel mixes.
And once a mechanical pump needs to be re-primed they usually take longer to do that than a comparable electric one. And once they get worn a bit or have a weaker diaphragm, re-priming can be a real chore.
Doesn't sound like yours is there yet, but might be getting close.
Another thing is a leaky rubber hose. Might not be a bad leak, but air is smaller than gas so will leak IN before you see liquid leak OUT and can cause the pump to be less efficient at pumping the liquid.
Good luck.
Paul
Do you have an open element air cleaner? That might allow fuel to evaporate quicker out of the float bowl.
Might also be the float level is now lower, meaning less gas to evaporate before empty.
Also might be draining back out of the line due to an older, weaker pump.
Do you drive it much? How old is the pump? How long has it sat since it was replaced? A fuel pump that is not used much is way more likely to fail early than one that gets used regularly.
Especially with today's fuel mixes.
And once a mechanical pump needs to be re-primed they usually take longer to do that than a comparable electric one. And once they get worn a bit or have a weaker diaphragm, re-priming can be a real chore.
Doesn't sound like yours is there yet, but might be getting close.
Another thing is a leaky rubber hose. Might not be a bad leak, but air is smaller than gas so will leak IN before you see liquid leak OUT and can cause the pump to be less efficient at pumping the liquid.
Good luck.
Paul
Lead Driver
Joined: Jul 2017
Posts: 9,545
Likes: 1,156
From: San Jose, CA
Also, you can test the lack of gas theory by filling the float bowl with a little gas the next time you've had it sitting for a few days.
If that little gas lets the engine fire up instantly you know it's lack of fuel for sure.
If it still struggles to start, you have another issue.
Paul
If that little gas lets the engine fire up instantly you know it's lack of fuel for sure.
If it still struggles to start, you have another issue.
Paul
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Tuned
Joined: Apr 2013
Posts: 498
Likes: 53
From: Sweden
1TonBasecamp. Thank you so much for a very detailed answer!! Just came from the shop and actually found a very small leakage between a rubber hose and fuel line. I replaced the Hose and Clamps.
I have owned the Truck for 2 years and have been working a lot on the Truck (Sheet Metal work) but have not been driving it much. This time I just had to crank it alot more than usual. I dont know when PO changed the Fuel Pump.
I use stock Air Cleaner. I will check next time the Truck have been sitting for 2-3 weeks. Appreciate your suggestions a lot ! ! !
I have owned the Truck for 2 years and have been working a lot on the Truck (Sheet Metal work) but have not been driving it much. This time I just had to crank it alot more than usual. I dont know when PO changed the Fuel Pump.
I use stock Air Cleaner. I will check next time the Truck have been sitting for 2-3 weeks. Appreciate your suggestions a lot ! ! !
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