Runs, and stalls...and runs, and stalls......

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73mako

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Joined
Jul 26, 2014
Posts
7
Hiya! I have a 1990 Safari Serengeti with a Ford 460cid.  It was sitting for 8 years when I got it.  I replaced the fuel filter(canister type) the fuel pump, drained the old fuel and replaced with new.  Turned the key and it started right up and ran smooth....for about two minutes.  Then acted like it ran out of fuel.  Turn the key, its starts up, runs for 2 min then dies again.  I have taken kinks out of fuel lines, replaced the fuel regulator, and checked for leaks.  I have replaced the oil temp sending unit and am now out of ideas. 
Anybody have any other ideas?  It acts as if its not getting any fuel.  Thanks.
 
Have you tried removing the fuel line where it connects to the carburetor? If not, put a clear jar under the fuel line, have someone crank the engine, and see how much fuel comes out. If it is only a trickle, you may have a blocked line, either before, or after the fuel pump. If the fuel comes out with a little bit of force, with the engine off, remove the air filter and look inside the carburetor throat while you activate the linkage. If you see fuel being sprayed inside at a constant flow, then you can rule out the fuel line and carburetor. If you have electronic fuel injectors, then disregard the carburetor part. Did you say you also changed the fuel filter?
 
I wonder if the new filter got clogged quickly and is not passing much fuel?  There may well have been a lot of gunk in the tank. Water too, and draining the tank may not have got it all.

Sometimes the simplest way to eliminate the tank/pump/line/filter as potential problems is to hook up another pump to a gallon can of gas and see if the engine runs ok that way. It takes a bit of effort to cobble it up, but it isolates the location of the problems if it works (or not).  If you still have the old fuel pump, you could even try it with that.
 
1990 should have throttle body fuel injection.    Will it keep running if you stay on the gas then stall out.  Or does it stall out whial idleing
 
It's likely some contamination has formed in the gas tank.  Disconnect and blow out the fuel lines.  As Gary stated, set up a separate fuel source with a different fuel pump and new fuel filter.    If it now runs, remove the fuel tank for cleaning, it may be possible to clean out the new, but now contaminated, fuel pump.
 
Its a carb. I disconnected the line at the carb and it flows well when cranked over.  But like I said, it starts and runs great, for two minutes.  On the gas, off the gas, doesn't seem to matter.  I will try the alternate fuel tank tomorrow.  Is it possible there is a screen in the pickup tube in the tank that could be clogged?  Or possibly another fuel filter that I am missing?  I haven't seen one from the fuel pump to the carb......Why would it have enough fuel to start and run for two minutes but then get starved for fuel?  Weird, and frustrating.
 
If you have already disconnected the line at the carb and fuel flows freely, then that indicates there is no blockage in the tank or the lines and I see no need to jury rig another source of fuel. Now the problem seems to be pointing to the carburetor.  Have you ever taken one apart? My guess is that the float may be bad, or stuck in the up or down position, or the carburetor injectors are clogged. If you can remove the top half of the carburetor you can check that the float moves freely up and down. Move the linkage with your hand and see if the carburetor injectors have a steady spray of fuel and also that fuel is reaching the float bowl. You may have to remove the entire carburetor and clean it with carburetor solvent and blow out all the orifices. If you are somewhat mechanically inclined, you should buy a carburetor tune up kit. I don't know how handy mechanics are with carburetors now days, since most cars are now electronic fuel injected, but you may have to take it to a shop.
 
    Before you take the carb apart check for a filter in the carb inlet. Ford used several different brand carburetors but most all of them have a filter behind the big nut on the inlet.  Remove it carefully, its not uncommon to strip the threads out if one is not careful. It's worth changing out that filter at least so it can be eliminated as a problem. Cheap and quick
    Like you mentioned the sock on the fuel pickup could be clogged or varnished over. Connecting the fuel line to another container of fuel (like a small boat tank) will tell you it that's the problem. Just because it pumps out a little fuel doesn't mean it can keep up with the needs of the engine. 
 
Tried the alternate fuel tank idea.  Still did the same thing.  I will check to see if there is a filter on the carb.  A carb rebuild is a last resort.  Plus, like I said, the engine purrs and throttles up just fine for that first two minutes, so its hard to believe that the carb is gunked up. 
 
Start and run the engine at 1500 rpm.  If you get the same 2 minute run time it may be an ignition problem.  An automatic reset circuit breaker would reset instantly allowing the engine to start again.  Do the dash lights stay on when the engine stalls? 
 
90 Ford should be fuel injected. Take a fuel pressure reading at the fuel line on the engine. Should be a fitting to do this. Check the fuel pressure right after you turn the key to the run position, then watch it right after you start the engine. If you continue to have fuel pressure you can rule out the pump or filter. If you lose pressure could be fuel pump relay. pump or filter.
 
Replaced the ignition module in the distributor to rule that out.  Still same problem but now runs rougher.  Disconnect the vacuum advance and it runs better all of a sudden.....?  WTH?
Also, had my buddy listen to the fuel pump and when I turn the ignition to start it runs, but as soon as the engine starts, the fuel pump stops!
Now what?  Where is the relay located?  It is not under the dash to the left of the steering column as some have said.  Also, again, it is a carb, not injected.
Is there some other sensor or relay that I am missing?
 
Most if not all vehicles are setup to run the electric fuel pump for few seconds when the key is turned on.  After that there has to be a signal that the engine is running to continue the operation of the pump.  Some are setup to look for a signal from the oil pressure sensor.  Do some research into the method of operation for your fuel pump.
 
straight wire the pump but be sure you have oil pressure. They cnhide the relay almot anywhere on an RV. On our chevys the relay is on the fire wall by the AC evap but that is our trucks. Jeep has it on the fuse block.
 
Sounds like pump runs with key in start position and not run position. Whoever said relay, may be on to something. Many carb fuel pumps run constantly while engine is running.

Bill
 
Ok, still frustrated!
I have now replaced the ignition switch and the ignition module.  And it does the same damn thing!  Runs for about a minute then dies because the fuel pump is not continuing to run after it is started.
I am getting to the point where I am just gonna sell it because I am just done tinkering on it and replacing parts that are not the problem.  I know that the problem is probably a $20 fix, but geez this is ridiculous!
Any other ideas?
Or does anyone want to buy a really nice rv with a fuel delivery issue?
:-\
 
I have a 1990 ford.  replace your TPS (throttle position sensor)  I had the same problem with my ford and my dodge.
 
Have you tried straight wiring the fuel pump yet...sounds like the relay to me.  also if the oil pressure switch does not see oil pressure it will not mull the fuel relay in.
 

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