Engine Fire again

[48bill]

Some of you may recall a fire I had in my F-1 in Auguist 2014.  It was contained in  the engine compartment and destroyed all wiring, hoses, the battery, carburetor, and distributer above the valve covers.  It also burnt the paint on the hood.  I repaired it in August 2014 and having been driving since.  That fire started after I had driven the truck, parked it and went in my house for lunch. While I was away from the truck it burned and put itself out. Temperature that day was in the high 90's.

On Monday, temperature low 50's. the truck stalled while I was driving at about 30 mph.  I popped in neutral to try to restart but to no avail.  I coasted to the side of the road and opened the hood to look for an obvious problem with wiring or fuel.  There were flames around the carb on the intake manifold.  I put them out with the extinguisher.  

There was no damage to the wiring or hoses.  Extinguisher powder covered everything and I did see a dark spot when checked smelled like gas. This was behind the carb.  A couple of friends and my mechanic, who had the truck for 2 days, suggested that it might have been a stuck float which allowed gas to spill onto the hot intake manifold and ignite.

The F-1 has a 425 cid Caddy engine with a quadrajet. electric choke and stock HEI distributor.

Any ideas.

[chimp koose]

carb job . Maybe the needle and seat got some crap in it and hung open?

[sirstude]

If a quadrajet, make sure you replace the composite float, they will soak up gas and flood.

[Mikej]

Do you have a spark loose under there?

[wayne petty]

put a 10 micron fuel filter before the pump inlet...  or right at the pump inlet to protect the pump check valves and your carb needle and seats from getting held open with the sediment out of the gas tank and fuel lines..  it does not have to come from your truck. it comes from gas stations also..

drop Neodymium Magnets‎ into the fuel tank when you have the sending unit out be toss them in away from the end of the sending unit float arm.. i have stuck the float arms to the bottom of the tank..  the magnets will just live there forever and collect sediment..



i use the 1990 ford ranger fuel filters as they are 10 micron.. brackets are easy to get off ranger pickups and others..  they will work with 5/16 or 3/8 fuel hose with clamps.. and every parts store and big box store has them for around 10 bucks. except they are big and ugly... but its better than having cold start and stall ... cranking for a minute or two every morning.. because the sediment has allowed the fuel to drain all the way back to the tank..

when i install these..  i usually perform a full flow, ignition disabled cranking test 3 times... each one 15 seconds of cranking so the fuel pump can flow full speed clean fuel thru the pump..  i then hook up the carb.. get the engine started.. using a pair of long nose pliers.. i squeeze the new fuel hose between the filter and the pump inlet.. take the RPMS up so the fuel is used up in the carb and the float/s drop... just as the engine starts to stumble.. i release and the pump pulses thru the line at full speed.. thru the wide open needle and seat.. this will usually blow when performed at least 2 times most of the residual debris out of the needle and seats..  

this cures the hot idle vapor lock issues... where the check valves are leaking .. reducing the fuel pressure to the carb. . the heat from the engine causes the low pressure fuel in the lines and in the pump cavity to boil.. the vapor pushes the fuel back to the tank.. leaving you with a lean motor..  expanding the pistons.. wedging them in their bores... making hot restarts an issue.  as there is no fuel to start it and excessive draw on the battery while cranking.

i have been fighting this issue since 1983 or so...

i was trying to cure the cold start and stall.. i hooked up a  clear vinyl hose to the fuel line at the carb inlet.. i cranked the engine to fill the hose that was looped up on the hood latch.  when i stopped cranking the fuel vanished..  went straight back to the tank.. i was able to blow bubbles in the tank..