I have a bobcat 732 with a no start problem. ford 1.6l gas engine. initially I found 2 burnt valves in cyl 1 and 2 but after replacing/lapping all valves and new head gasket I got the engine to start and run for a few minuets then die and nothing since. latest compression test readings- no 1- 30psi no 2 -90psi no 3-120psi no 4-120psi I would think if worn piston rings were the problem the numbers would be lower across the board? also with 2 good cylinders shouldn't it at least try to start? plugs are wet and I have blue spark. when it was running briefly it was not smoking like it would if the rings were worn. also I adjusted the valves starting with no 1 at TDC then moving the crank a 1/2 rotation to adjust each other cylinder in the firing order, is there any different way I should adjust them? -thanks
It should start and run with two at 90 and two even worse, so those compression readings aren't keeping it from starting. Did you try a compression test or leakdown with a teaspoon of oil added to each cylinder to seal the rings? Sometimes the cylinder walls get washed down with gas and the rings won't seal enough to start, especially after not running for a while. Did you try starting fluid? even though the plugs are wet, could have bad gas/water. Double check everything you did in the repairs, loose connector, ground, loose distributor?
if the engine and machine are still in their "original condition" there are 2 electric fuel shutoff solinoids. one is at the base of the carb other is inline in the fuel line in the engine compartment. check your points for pitting and corrosion, as well as ALL your harness connections. check cap/rotor for corrosion :drinkup
Double check the valve lash for #1 cyl, something may have gone awry, if an intake is stuck open a little you may have some issues with intake manifold? Long shot.
Well I finally got the engine to start for a few seconds by pouring gas into spark plug holes. that confirms a carb problem so I rebuilt and thoroughly cleaned the carb and I'm still having the same problem. I don't know what else to do other than replace the whole carb but really don't want to spend 300$+ just to have the same problem in the end. If anyone has any other ideas please chime in! By the way it's a zenith model 68 updraft carb
ive never had any good luck rebuilding a carb for a ford (or mitsubishi) gasser. they NEVER run right. are you getting gas to the carb? and is it filling the bowl? :drinkup
Yes, I have good flow from the tank and the bowl is always full when I take it apart.
Did you check the valve lash? Do you have vacuum at the carb intake when cranking? 90 psi is low, 30 psi compression I would think you could get with no rings, so there's got to be a valve problem or something else in that cylinder.
Yes I have adjusted the valve lash and all are within spec I am also unsure as to why that cyl is was so low but right now I just need to get it running. When I got it to start it did run on all cylinders so I'm pretty sure it's not that cyl that's keeping it from running. I chased a possible vacuum leak already and replaced the intake manifold gasket but to no avail. I have plenty of vacuum at the carb.
Try running it on an oil squirt can like this for a couple minutes and see if it picks up on it's own. Be Careful of a backfire and don't burn off your eyebrows, it's not the safest thing to do.
Today I removed the spark plugs and with each cyl at TDC I used compressed air to clean and dry each piston, did the same to the plugs to ensure everything was bone dry and reinstalled them. Then I set full choke and cranked the engine for a good 20 seconds ( carb bowl had fuel in it) and the plugs were still bone DRY. Has to be a blockage in the carb somewhere I would think but I have cleaned and inspected every part of it countless times and everything is clean as a whistle??
What about that fuel solenoid in the carburetor base that Crewchief mentioned? Is is possible it controls fuel flow from the carb bowl to the main jets?
There is no electric fuel cutoff solenoid on this carb it's a model 13805A. There is only a non adjustable main jet.
try this, check your coil output. Low winding should be 1.5 to 3 ohms and the high end output should be at min of 5k ohms. A weak coil will show the same symptoms.