Priming mechanical fuel pump
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Posting Guru
Joined: Jan 2013
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From: Wichita, Kansas
Priming mechanical fuel pump
Well I had the battery out of my truck for quite a while now due to electrical work that was being done. Now that I finished, I put the battery back in and expected a quick and easy fire up. Not the case. Instead she was out of gas (it took me about two hours to determine this as I had to figure out which tank was the one feeding the motor and had to check connections all the way down the line, etc.). Well I put three gallons of gas in the tank and this confounded thing would not start. I poured gas into the carb directly and it fired right up. So basically, the motor has no prime in the system. How do i prime the dang system?
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From: Wichita, Kansas
It only ran for about 2-3 seconds. It didn't go for very long, since I dumped 99% of the gas from the red can into the fuel tank. I got till after the weekend to go get some more gas for the red can
Cargo Master
Joined: May 2011
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From: Northern California
If you dont mind gas in your lungs, try disconnecting the fuel line at the carb and sucking... If you have a clear fuel filter you can see when the fuel is approaching. Once you have some in the pump, reassemble... It should quickly prime the rest of the system after a few cranks.
If it doesnt... Maybe a bad fuel pump.
If it doesnt... Maybe a bad fuel pump.
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From: Wichita, Kansas
I tried to tell my dad about the sucking it through last night...and he kind of shot me down. I do not have a clear fuel filter yet. I do not feel any vacuum through the line right after the pump when cranking, but it doesn't really push my finger up all that hard.
Cargo Master
Joined: May 2011
Posts: 2,388
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From: Northern California
I was having a similar issue... The pump didnt like pulling on air. Try a vacuum of some sort; you need to get fuel in it.
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Hotshot
Joined: Jul 2005
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From: Middle Tn.
Make sure all of the rubber lines behind the pump are new. They can and will suck air. If good the the pump is bad or installed incorrectly. If every thing is good then 15 to 20 seconds of cranking should provide plenty of fuel.
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Fleet Owner
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From: Creedmoor, North Carolina
I agree with your dad, you don't want to be sucking on a gas hose. If you poured gas into the carb and it fired you know the engine will run, how well is another issue.
I have never removed a tank side hose from the fuel pump when gas didn't run out by gravity. Try that first to see if gas is flowing from the tank. If yes, reconnect that hose and remove the other side up on top, poke the end into a pop or water bottle. Turn the engine over to see if any gas is being pumped. It has to be pumped to run, sucking on the line is of no value except for bad health in the future. If no work on getting it unclogged.
You might want to pick up a new or reman pump on the way there, should you not need it you can take it back for a refund.
John
I have never removed a tank side hose from the fuel pump when gas didn't run out by gravity. Try that first to see if gas is flowing from the tank. If yes, reconnect that hose and remove the other side up on top, poke the end into a pop or water bottle. Turn the engine over to see if any gas is being pumped. It has to be pumped to run, sucking on the line is of no value except for bad health in the future. If no work on getting it unclogged.
You might want to pick up a new or reman pump on the way there, should you not need it you can take it back for a refund.
John
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Posting Guru
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From: Wichita, Kansas
Okay guys. The engine will run with gas in the carb. We poured gas into the outlet of the pump and it pumped it through the filter and into the carb. So what is going wrong?
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From: Wichita, Kansas
I changed the message because I reread it and was confused myself. I disconnected the line from the fuel filter to the fuel pump and poured it straight into the outlet side of the fuel pump.
Cargo Master
Joined: May 2011
Posts: 2,388
Likes: 138
From: Northern California
Sounds like a bad fuel pump then... Your sure the lines arent crossed? Aside from being shot, incorrect installation is the only other possibility; these things are really straight forward.
You can try pump fuel through it while disconnected from the carb. A few extra feet of fuel line help with this. Just stick the inlet hose into a bottle of fuel and see what happens when you crank. It should suck. If it doesnt try the other hose in case you got them mixed up. If no pumping replace pump.
Your OP indicates it was running before a battery issue... You didnt do any other maintenance while it was down?
You can try pump fuel through it while disconnected from the carb. A few extra feet of fuel line help with this. Just stick the inlet hose into a bottle of fuel and see what happens when you crank. It should suck. If it doesnt try the other hose in case you got them mixed up. If no pumping replace pump.
Your OP indicates it was running before a battery issue... You didnt do any other maintenance while it was down?