I need some help with a 742 with ford 1.6l. Currently it has a brand new electric fuel pump,brand new fuel filter, and a pertronix electronic ignition. Ran last year with a minor hiccup every once in a while, nothing major. This year, would not start. Figured out there was no gas getting to the carb, hence the electric fuel pump. Did not take out the old pump, not sure if this matters or not. Anyway, put the electric pump in and it fires up, but shuts down after approx. 20-30 seconds. Turn the key, and it fires right back up for another 20-30 seconds. I am lost at this point. I am not sure if the fuel is the problem or possibly something electrical. Any and all help is greatly appreciated! I will try my best to answer any more questions! Thanks!
742 help
- Thread starter rhellman
- Start date
The old mechanical pumps fuel lines are no longer connected. from tank it goes to new electric fuel pump and then to carb. I can keep the motor running by spraying starting fluid in, so I am fairly positive its a fuel issue. Its like the carb bowl runs dry, but if that were the case, would it start right back up?
does it have the electric fuel solenoid on the carb bowl? Sounds like the float valve in the bowl is sticky and not letting fuel in very fast either.
yes, it has the solenoid on it. I have the carb out and the needle seems to move freely. This Zenith carb is a bit different as other carbs I have worked on the float needle was attached to the floats. my guess is on the zenith, gravity takes the place of the spring? Can the machine run with the solenoid removed? From my understanding, this shuts off fuel to the carb when you turn the machine off.
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Just from my experience with a 632 with the same motor and similar trouble. It will run with or without the carb solenoid in it, I took it out and plugged the hole, made no difference so I put it back in. Cleaned the carb endlessly and put a new fuel pump on also. It turned out to be the distributor had moved and the timing was off quite a bit. The vacuum advance on those engines does go bad also. My engine was in very good condition and it was just a last resort that I checked the timing. The float does just gravity operate, it does not hurt to take some very fine wet or dry emery and polish the sides of the needle though.
Our famous govt gas, even w/ Stabil in it, would stick the Anti-dieseling solenoid on the carburetor on mine and make starting problematic so I removed it for now. [Solenoid=$160.00 toolbox trinket. /rant] I also have the float level set 1/32" - 1/16" higher than the book calls for. Starts Much better and doesn't take 5-8 minutes of warm-up before you can move w/o stalling. When you assemble the carb put the fuel hose on it and blow through it to be sure the float is open in the operating position and then invert the carb and blow again to be sure the float is closing, free and not scrubbing on the sides of the bowl. The two pontoons are tricky to keep aligned while adjusting the level. For this you can only go by eye but the pontoons must be free or they won't respond to a fuel level drop fast enough to not cause stalling. -Dick
Thanks for the tip. I removed the fuel solenoid and plugged it in, no movement at all, so I know that is bad. Gonna just get a plug for that. The carb is very clean now, completely gone through. My timing is good, what makes me think its not timing is I can keep it running with starting fluid when it starts to die. Everything is telling me its running out of fuel, but I know there is fuel still going to the carb.
Cyclone Ranger
Well-known member
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- Dec 12, 2011
- Messages
- 101
You might consider pulling the fuel line off at the carb and placing it into a can where the flow rate can be examined. Have a friend turn on the ignition and verify you have adequate flow for at least 30 seconds. It is possible the screen in the tank has clogged and is restricting your fuel flow. This would also verify the fuel pump is wired correctly and the tank is properly vented.
Cyclone Ranger
Well-known member
- Joined
- Dec 12, 2011
- Messages
- 101
If you fuel flow test fails to provide consistent and adequate fuel flow for at least 30 seconds some other places to look for the restriction are the electric safety shutoff near the firewall passthru and the fuel petcock on the passenger side of the firewall also near the passthru. The screen on the electric safety shutoff is especially small and easily clogged if dirt gets through the filter. The fuel petcock should be in the full open position which may be several turns out.
awesome info. I will indeed try this before putting the carbs back on! thanks!
The threads are straight. I made a plug from a bolt that would screw in and fit. Saw it off to about 3/8"-1/2" long and use a fiber washer. Really sounds like the float is scrubbing on the side of the float bowl. Ask me how I know.
It was the fuel pump all along. Would quit running after 30 seconds. thanks for all the help
