Community Forums

cubano222 · 03-15-2011, 02:13 PM

How do I test the fuel pump on my Onan BFA 4.0 generator? It use to run great but now it will not run. I spray starter fluid in the carb & it starts but runs for a second. I took the plate off the bottom of the cylinder thing & checked the filter, it looks brand new. I ran a fuel line from the pump to a gas can & it will not pull gas. Should I be able to hear the fuel pump run like in a car? There is a local RV mechanic that will fix it but he charges $70 an hour. Will it be worth it for me to spend $60 on a Airtex E8016S external pump to see if that corrects the problem?
Thanks for your help,
Jerry

Jack R · 03-15-2011, 03:38 PM

cuban222

I think I would pay the $70 to the mechanic. If what you are thinking doesn't work than you will have $130 tied up. $60 PLUS the mechanic.

jack

Kjlunda · 03-15-2011, 06:09 PM

Quote:

Originally Posted by cubano222

How do I test the fuel pump on my Onan BFA 4.0 generator? It use to run great but now it will not run. I spray starter fluid in the carb & it starts but runs for a second. I took the plate off the bottom of the cylinder thing & checked the filter, it looks brand new. I ran a fuel line from the pump to a gas can & it will not pull gas. Should I be able to hear the fuel pump run like in a car? There is a local RV mechanic that will fix it but he charges $70 an hour. Will it be worth it for me to spend $60 on a Airtex E8016S external pump to see if that corrects the problem?
Thanks for your help,
Jerry

I would make sure you have power to the fuel pump before I paid someone to check the Gen.

whem2fish · 03-15-2011, 07:29 PM

first check for power to pump if ok get a pump of ebay low volum low pressure i did not remove the old pump just instaled before the pump
dave

TQ60 · 03-15-2011, 11:30 PM

There may be an interlock to prevent the fuel pump from pumping out your tank in the event of a broken line or engine failure.

Get a voltmeter and locate the power connection on the fuel pump, have a helper hit the starter swithc and see if any voltage is indicated on the post, locating a manual is a great help.

If no voltage then lose wire at selenoid or other interlock.

A clip lead or test wire, use small wire or one with a fuse, you can jump 12 volts to the post and see if the pump runs.

Before you spend much time download a manual, locate the troubleshooting section and follow the steps.

Placing an external fuel pump inline can be deadly, one needs to interlock the fuel pumt to the engine operation, failure to do it correctly may allow a flow of raw fuel into an open compartment creating a fire/explosion hazard.

whem2fish · 03-16-2011, 04:42 AM

TQ60 please explain what i did wrong so i can fix. i took the original hot wire from the old pump and ran it to the new one
thanks dave

cubano222 · 03-16-2011, 07:59 AM

There is power going to the fuel pump but I don't hear it run. Like I said, with starter fluid, it starts up right away & as long as I keep spraying in the carb, it will run. The RV mechanic told me it sounds like the carb is dirty or the fuel pump is shot. All the fuses are good. The filter is clean. I have read several ports where others have used the Airtex low pressure pump with success, thats why I thought I would try it.
Thank you for your help,
Jerry

LGriffin · 03-16-2011, 06:50 PM

I have a 1994 Pinnacle and I had to replace the fuel pump on the gen recently. The electric pump is a vane type and doesn't make a lot of noise. I had to drop the gen in order to be able to work on and remove the pump. I replaced it with a Napa P4070, look just like what I took out, cost < $60.

btw I also replace the fuel filtr with a barb and a fuel filter from a air cooled VW.Now I can see if I have gas to the the gen.

Larry

TQ60 · 03-17-2011, 09:44 AM

Quote:

Originally Posted by whem2fish

TQ60 please explain what i did wrong so i can fix. i took the original hot wire from the old pump and ran it to the new one
thanks dave

If you used the existing power connection for the old fuel pump for the new one then you are likely OK, as the safety devices are between the battery and the fuel pump.

If you want to verify it you could/should contact the maufacturer of the generator to confirm what you have done is "safe".

Some of the older Onan engines use a diaphram pump, same as old type automotive with a electomagnetic motor, they were designed for old mix gas, and with new gas and age the rubber goes bad and freezes the whole thing up, they stop making the clicking noise and either do not draw current if stuck in down position or constant draw if stuck in up position.

Factory replacement is best if can be confirmed to be compatable with current gas, this bodes better if ever need for insurance claim.

If any other type of fuel pump is added then any fire damage linked to the generator will be an issue with insurance unless the manufacturer of the generator states it is a valid mod, or it is widely accepted as a "industry standard".

whem2fish · 03-17-2011, 10:27 AM

thanks

leadman · 03-17-2011, 03:50 PM

Remove the fuel line from the fuel pump to the carb and run it to a spare gas can. Crank the engine, if fuel comes out in a full stream it is probably o.k., if not replace the pump. You will probably have to buy a longer section of fuel line to do this, but then you will have new line to replace the old on the gen set.
If you get a good stream, but the unit still will not run you can install a fuel pressure gauge on the end of the extended line. Off the top of my head I would expect around 4 psi. If anyone has the exact spec please post it.

If you have flow and pressure but it still won't run you may have to have the carb looked at.

It also could be a spark issue as starting fluid will sometimes cause a gas engine to run without spark, but rare. If you can access a spark plug wire you can install a spare spark plug on the end of the wire and ground the threaded part of the plug to the engine. When you crank it you should see spark between the electrode and ground tab.

ccook129 · 03-17-2011, 04:09 PM

Make sure you have the gas tank more than 1/4 full

leadman · 03-18-2011, 10:12 PM

Yes, make sure you have plenty of gas in the tank. My Itasca manual says the generator cuts off when there is a 1/4 tank, but it actually happens at about 3/8 of a tank.
If you have plenty of gas in the tank you can run the inlet side of the generator fuel pump out of a gas can to check it. If it runs the pick up in the tank for the generator could have broke off or the fuel hose could be cracked also, so you may want to check this by using a hand held vac pump with the brake bleeder container in-line. You should be able to pull gas into the container easily.

pwf16129 · 03-20-2011, 07:42 AM

ck to see if the pickup in the tank has broken off I bought my 1985 midas the gen set would not run ,found the pickup tube had fell into the tank could not buy a new one installed a bulkhead fitting with home built line, into the new tank that's another story, and ran a new fuel line with in line filter and my fuel problem was solved.
but the fuel pump is very quiet I have a bypass switch to run the pump with out cranking the engine , that is so i could also ck the fuel shut of just below the fuel pump

best wishes frank,cricket and harley the dog