onan generator question

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dog_soldier

dog_soldier

Well-known member
Joined
Aug 3, 2008
Posts
62
on the 84 coachmen we just got ,the generator wont start. i got fuel to the fuel pump after drinking a little of it. after cranking it still wont get fuel past the pump.
what im wondering is can i put a car electric fuel pump on it and have it take the place of the one on the generator?
im thinking yes but want to hear from others that know more about these generators then me.
 
there is a generator troubleshooting guide at www.flightsystems.com good information.
You need to worry about fuel pressure and some other details not easily available for the pump you have.  Previous owner replaced mine with car unit and I had lots of problems.  Went back to OEM and okay.  Not sure if pump was really the problem or the use of wire nuts and wire splices (poor workmanship).
 
Most universal and automobile fuel pumps, work on 12v. If you check voltage at the positive lead that goes to the fuel pump when crancking, you will see a voltage of around 45 to 50v. When mine went out, I replaced it with a pump for a different model onan genny that was way cheaper that the exact replacement. On my case, the pump was pumping, but the rubber diaphram inside was torn. If you have the BGE model 4kw onan, then I can give you the part number from the one I got, and maybe it will be easier to find, since that same pump is used for a lawn mower tractor.
 
i found one that pumps at 2.5-3.5 PSI that i can hook up with a off on switch.
my generator is a 6.5 KW but the pump you found may work. how much was it ? if you dont mind me asking.
 
i got it running this morning. yesterday i srrayed some pb blaster into the top part of the pump. i went out this morning to check the volts and when i hit the start button it fired right up and scared the heck out of me.
thanks everyone for the help  ;D
 
all of the onan generators i have seen the fuel pump is VERY low pressure. 1 to 3 lbs max.  i just ordered  this one 

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=400107342303&ssPageName=STRK:MEWNX:IT

will let you know how it works



bob
 
Fred G. said:
If you check voltage at the positive lead that goes to the fuel pump when crancking, you will see a voltage of around 45 to 50v.
Click to expand...

Why is that, and where is that 50V coming from?

What is that 50v being measured with? Is the cranking messing up the readings or do they really use 50V?

-Don- SSF, CA​

 
supermod38 said:
all of the onan generators i have seen the fuel pump is VERY low pressure. 1 to 3 lbs max.  i just ordered  this one 

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=400107342303&ssPageName=STRK:MEWNX:IT

will let you know how it works

installed fuel pump today and it works great. 8)





bob
Click to expand...
 
Just a little note for folks inserting quotes.

  After you have inserted the quote one must "spacebar" past the last "quote" command entry on the screen. Then just hit enter and then continue.

Just trying to help... carson

 
[quote author=carson]After you have inserted the quote one must "spacebar" past the last "quote" command entry on the screen. Then just hit enter and then continue.[/quote]

Thanks Carson, but it's right arrow, not space bar.

One thing I'd suggest folks do is go into your Profile, look for the option to Modify Profile, then Look and Layout. Scroll down and check the box labeled Return to topics after posting by default, and don't forget to click Change Profile at the bottom of the page to make the change stick. Then, every time you post a message, you'll come right back to the topic, and you can see if it posted OK.
 
DonTom said:
Why is that, and where is that 50V coming from?

What is that 50v being measured with? Is the cranking messing up the readings or do they really use 50V?

-Don- SSF, CA​
Click to expand...


I have the exact same question. Mine is showing approx 50 volts. I'm going with an aftermarket pump. I'm scared I'll fry it. I know this is an old thread but anyone? 

Thanks!
 
To answer your "Can I use a fuel pump designed for a car" the answer is ... Perhaps. most likely not.

Fuel pumps. be they designed for a Automobile or for a generator.. Are designed to deliver at a specific pressure.. Now the electric fuel pumps and the cam driven ones I have dissassembled both worked the same way. Sort of.

On the cam driven the cam pressed "Down" on a lever (may be up or down or sideways) compressing a spring and pulling a diaphram expanding a chamber and "Sucking" fuel out of the tank. then as the cam rotates the lever is released and the tension on the spring delivers fuel to the carb.

On an electric the cam is replaced by an electromagnet and the turning of the cam by a switch.
The sprng still sets the poressure.

Pressure is DIFFERENT for a car and a generator. I THINK the generator is a "low Pressure" pump (relatively) but please do not take that as gospel since the key word was THINK.  Not sure. Others here are.

But I'd not use a automotive fuel pump on a generator. Pressure is wrong.
 
1.5 to 4 psi is what I found this summer when my 5500 quit. That info came from a Cummins Repair Center in New Mexico.
 
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