520H Not Getting Fuel

[TC10284 111]

Got a 3120OE01 1988 model 520H. I used it last week to mow the lawn and it worked fine. This week, it is not getting any fuel. 

I have recently put on a new fuel pump, fuel filter, and new shut off valve/rubber grommet.

To diagnose, I have:

Put on the old fuel pump - no change.

Blew out the fuel lines with an air hose. No blockages. I can't see that it is collapsed or pinched anywhere. I can blow through it using my breath and it isn't difficult.

I have taken off the fuel pump and tested to make sure the hose coming from the engine that produces air/suction is working. It blows and sucks on my finger. 

Engine will run when I pour some fuel into the carb.     

I have pulled the hose off at the Outlet of the fuel pump and the majority of the time I can't see anything pumping out. But there was a time or two that it squirted about two to three inches high. However, after I thought it was working and reattached the hoses, it stopped pump. Pulled it back off, not pumping again. 

Edited May 25, 2018 by TC10284

[boomers_influence 106]

tc

try a divorced fuel tank located on the top of a 5 foot stepladder,

with the fuel line from the tank hooked directly to the inlet of the carb.

 

thank you. boomer ( the used onan engine parts guy, also NOS and new )

 

[TC10284 111]

18 minutes ago, boomers_influence said:

tc

try a divorced fuel tank located on the top of a 5 foot stepladder,

with the fuel line from the tank hooked directly to the inlet of the carb.

 

thank you. boomer ( the used onan engine parts guy, also NOS and new )

 

I'm sure it would run like that, even though I don't have any extra fuel line to try it. 

Is that supposed to help get the pump working again? Hope that doesn't sound rude. It's not meant that way. 

Edited May 25, 2018 by TC10284

[TC10284 111]

I even tried priming the pump by filling it with gas using a syringe. It does not even move the gas after I do this and try to turn the engine over. 

Edited May 26, 2018 by TC10284

[cleat 7,123]

Is the vacuum line in good shape that connects to the fuel pump ?

[TC10284 111]

5 minutes ago, cleat said:

Is the vacuum line in good shape that connects to the fuel pump ?

 

I'm planning to take the shroud off tomorrow to check on that. 

[BESTDOGEVER 218]

Pull the gas cap then try it .

[TC10284 111]

11 minutes ago, BESTDOGEVER said:

Pull the gas cap then try it .

 

Tried that one already. 

 

Also, this may be relevant - see my later posts here: 

 

[TC10284 111]

14 hours ago, cleat said:

Is the vacuum line in good shape that connects to the fuel pump ?

 

I'm having some difficulty getting the engine/flywheel shroud off. I've removed the bolts on the sides and near the top. 

Do I also need to remove the throttle cable and governor arm spring? 
Anything else? 

[cleat 7,123]

There are 2 bolts near the bottom, 1 bolt by the coil. You may need to pull the coil as well.

 

Yes, you need to remove the cable and spring.

 

Cover is a pain in the a** to get off, you need to get it just right.

 

If you can get the rear cyl head cover off, you may be able to see the vacuum line from there as well.

 

[TC10284 111]

5 hours ago, cleat said:

There are 2 bolts near the bottom, 1 bolt by the coil. You may need to pull the coil as well.

 

Yes, you need to remove the cable and spring.

 

Cover is a pain in the a** to get off, you need to get it just right.

 

If you can get the rear cyl head cover off, you may be able to see the vacuum line from there as well.

 

 

Finally got it. The vacuum hose didn't look cracked or collapsed. But I'm replacing it anyway. Also took a fuel pump off another, known working 520H that is having the engine rebuilt, to test and see if it's possible I have two bad fuel pumps (I'm doubting it). 

 

[TC10284 111]

I tried the fuel pump from my known working 520H. Didn't help. I noticed I could pull off the inlet fuel hose even with the squeeze clamp on it. So that gave me an idea that perhaps it it sucking air at the inlet. I tested this by temporarily using a zip tie and tightening as much as I could. This seemed to get the pump working again and finally got it to run. Then I went and got some hose clamps that you screw to tighten. 

Also replaced the hose running to the engine and back of the fuel pump. 

 

SO FAR...it is working. Hopefully it will stay this way. I'll give a try tomorrow and then a few days after that to see. 

 

Maybe this was the cause of the surging issue in my other post?

Edited May 27, 2018 by TC10284

[cleat 7,123]

I would replace the fuel line if it is at all bad.

 

Sounds like it might be getting hard.

 

Quality 1/4" fuel line should fit all connections securely even without a clamp (but use one anyways).

 

[TC10284 111]

An update for anyone else that may have this problem:

 

I'm pretty sure I finally fixed this for good. 

 

I went out the other week to start it up and saw that there wasn't any fuel in the filter and turning it over didn't pump any into it. Started to get frustrated again since I've dealt with fuel problems on this one so often. 

I somehow, by luck, started squeezing the fuel line and felt a crack about three inches form the the fuel pump and when I squeezed it, gas got on my hand. You couldn't see it with your eyes if you didn't squeeze it. 

When I took it off fully, I saw that it had three cracks total. Two were about 2" long and one further down was 1" long.  

Replaced and so far, so good...