Rebuilt
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Rebuilt
Ok I just rebuilt my inline 6 and the compression on each cylinder was below 80 and it was running then well now they are all 90 and above well now I can't get it to start started with backfiring in exhaust got that fixed and now it's backfiring out the carb and not starting everything new is distributor, seals, gaskets,
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
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Check the timing it was set on 6 so I moved it back to one but I'm not keeping fuel pressure to the mechanical pump on the engine
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Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
6 what? 6 degrees? That won't make it backfire through the carb. Whatever caused that, needs to be remedied. Verify TDC #1 compression stroke and distributor rotor points just shy #1 spark plug wire terminal location. I'm betting it does not. You may be a "tooth off".
If the fuel pump is old, replace it. The diaphragm gets stretched and the fuel eats them up. A good pump must supply 1 pint in 30 seconds minimum at all times in all conditions. Backflush the hard line with shop air, maybe 10 or 20 psi. Replace any rubber fuel hose. Check for stale or varnished fuel etc.
If the fuel pump is old, replace it. The diaphragm gets stretched and the fuel eats them up. A good pump must supply 1 pint in 30 seconds minimum at all times in all conditions. Backflush the hard line with shop air, maybe 10 or 20 psi. Replace any rubber fuel hose. Check for stale or varnished fuel etc.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Ah, a six banger, I'm tracking.
Unfortunately even new parts are sometimes bad. Blow out the hard line back to the tank to be sure there is no obstruction. Also check for a bum fuel tank cap, that will not vent. It's easy to check fuel pump for volume, technically though need to check for proper pressure as well.
Both have to be in spec. Then, make sure the float level in the carburetor is OK. It may have been paired/adjusted to an old fuel pump with different flow output. Anytime the fuel system has new parts, the carb float level should at least be checked. It is a critical adjustment. Finally, adjust idle mixture and idle RPM.
Unfortunately even new parts are sometimes bad. Blow out the hard line back to the tank to be sure there is no obstruction. Also check for a bum fuel tank cap, that will not vent. It's easy to check fuel pump for volume, technically though need to check for proper pressure as well.
Both have to be in spec. Then, make sure the float level in the carburetor is OK. It may have been paired/adjusted to an old fuel pump with different flow output. Anytime the fuel system has new parts, the carb float level should at least be checked. It is a critical adjustment. Finally, adjust idle mixture and idle RPM.
Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
Remove the oil filler cap and you should be able see the #1 intake rocker. Remove the spark plug and get a piece of wood dowel ~12 long you can fit through the spark plug hole. Have someone turn the engine by hand until you see the #1 intake rocker open, keep turning until it closes, then insert the dowel into the cylinder, and turn until it's at its highest point. Remove dowel, replace plug, install distributor with rotor towards #1 cylinder terminal, start.
FTE Legend
Joined: Nov 2015
Posts: 30,831
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From: Angier, NC
The only place there are check valves is in the pump. To keep it simple 1 at the inlet & 1 at the outlet. The inlet opens to let fuel into the pump wile the outlet is closed or the pump would be pulling fuel from both side of the pump. The inlet closes and the outlet opens to let fuel co to the carb. Again if the inlet valve was open fuel would be pushed back into the tank.
Now why it will not hold PSI is before and after the pump is open to air. The tank is vented to air so cant hold PSI. The carb is also vented to air and cant hold PSI.
I don't even think a FI system holds PSI when off. That is why the pump runs for a few seconds when the key is first turned on, to build up PSI.
BTW I have an electric pump on my drag car with a fuel PSI gauge OUT SIDE the passenger area and as soon as the pump stops fuel PSI goes to 0.
So as posted if the volume test is ok the pump is ok.
Dave ----