# Confused Running



## two guns (Sep 22, 2014)

This is what I've found. Don't think there is anything wrong with the carb or the choke.
Got to be a fuel feed problem.. Drove it about
12 miles. Super ride, could not ask for better running. Then brought it home for about ten minutes. Cranked it up and ran for about 30 seconds and died. Spin the engine, it would fire up and run for about 15 seconds, with me pumping the pedal. This went on for about six cranks. Then got to thinking, this engine don't seem to be getting any fuel. So I took flashlight looked at glass in front of carb. Glass showed about 1/2 full. So decided to shoot a short shot of starting fluid into the air breather. Done that, engine started up and ran again until I put it up in the back shed. Now, to me, seems like it is loosing it's prime or just something. Wonder if these "fuel pumps" stop and go. For when I "HELPED" it with the 
shot of starting fluid, it spun quickly as expected and run again like new. Could it be the relay going out? Or the pump.
But I have figured just becouse the glass has got half fuel in glass to show, don't mean it's going to run. For the whole time it runs, it has half level of fuel in the glass, and when it's not running, and just spinning over. It shows half full level of fuel in glass.
What is your idea on this ?


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## smj999smj (Jan 1, 2006)

I'm assuming this is for the 84 720 truck? The fuel pump's job is to supply fuel pump to the carburetor, so if there is fuel to the middle of the sight glass on the carburetor, it's not a fuel pump issue. If you say that it stops running while there if fuel in the bowl, but it will start and run when you spray starting fluid into the engine, it would lean more towards a carburetor issue as it's not getting the fuel it has into the engine. If, when it does run, it appears to be running too lean, then I would first check the intake manifold gaskets for potential leaks, as well as the vacuum hoses for splits or disconnected hoses or for a sticking open EGR.


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## two guns (Sep 22, 2014)

..... or should I say, it's almost to the "dot" in the middle of the glass.
We just disconnect the fuel line from the carb. Disconnected it from the pump.
We blew air from the carb line toward the pump ( with it disconnected) and blew again from the pump to the tank. ( with the gas cap off ) seem to have no retrictions.
Went ahead and changed the fuel filter.
NOW, 
We installed a guage "in-line" from the pump to the carb, with the line and guage running into the cab to see if it ever drops or what. If it does. I am going to blame the
fuel pump relay.
Going on a test run now ....


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## smj999smj (Jan 1, 2006)

The sight glass is used to determine the float level; the gas should be right in middle of the window. If the fuel pump was faulty, you wouldn't see any gas through the sight window. If it stalls out or doesn't run and you see the fuel in the middle of the sight glass, your wasting your time bothering with the pump as you have visual evidence that fuel is getting to the carb.


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## two guns (Sep 22, 2014)

We blew back on the lines with massive air pressure. Disconnecting the pump and all first. Took off the gas cap to vent what air we blew threw it from the lines. Blew from filter back to the tank, and from carb to the pump. Just making sure there were a great passage of fuel that could flow correctly. 
We put a fuel pressure guage in-line. Tee'd off the main line and run a guage around the truck bed and threw the back window. Ran the truck 11 miles. No problem.
Kept a constant 3.4 PSI on the guage. 
We cranked the truck up cold, the choke worked properly. It kicked back down properly.
Don't have a clue what is going on. Thinking now it just might be the fuel pump relay acting crazy. For one, it's a intermediate problem. Can't really pin=point when it's going to happen. 
THEN, here it comes. 
I took a peek at the relay. And on the very bottom corner of the relay. It was like
wet with some sort of oil or something. Just a small tiny drop. It looked like it came from out of the relay. I took a picture and will post if I can. There is NO WHERE that this tiny micro drop of wet/oil could have come from but inside the relay. Did not know there was any type of oil or something of that nature inside the relay. There is no doubt, it come from inside the relay. Now what it is, don't have a clue.
I will see if I can post the picture ....


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## two guns (Sep 22, 2014)

smj999smj,

I have sent you a PM. Take a look >>>>>

Thanks, 
Two Guns


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## smj999smj (Jan 1, 2006)

Could be some resin inside the relay has melted. Just replace the relay. Whether that's your problem or not, I cannot say. Try it!


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