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454 cold start problem -- choke issue??

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contender31

Regular Contributor
Hello again from warm sunny south Florida - having cold start issues with my 1990 454 crusader 7.4 with a quadrajet 4 bbl. If I use ether sprayef into the carb the engine will start and run as normal but after sitting a couple of weeks it wont start without spraying ether in the carb throat. I have recently changed out all the filters including the secondary carb filter. Again the engine will run as normal after using the ether to start it. I am thinking it is a choke issue??? FYI manual fuel pump and choke and carbs were refurbished last year

Thanks in advance for any tips or thoughts
 
Highly likely that the fuel is just evaporating out of the bowl when the engines "sitting a couple weeks"....welcome to a byproduct of modern "fuel".

FastJeff has posted a few times on his 'priming system' but it requires electric fuel pumps...not a lot of options with the mechanical pumps.
 
makomark said:
Highly likely that the fuel is just evaporating out of the bowl when the engines "sitting a couple weeks"....welcome to a byproduct of modern "fuel".

FastJeff has posted a few times on his 'priming system' but it requires electric fuel pumps...not a lot of options with the mechanical pumps.
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I would agree on evaporation except the other engine is starting fine??
 
I wouldn't think the choke is essential down in south FLA...that said, have you checked it?

You can use a probe to check the fuel level in the bowl; use one of the vent stacks in the air horn. a coffee stirring stick works well. It will end up on the float. You can use the other carb as a reference...
 
Agree on the choke but typically after sitting a week or so I have to pump the throttle a few ( 3-4 ) times to get the engine to start, the port engine starts fine but the starboard will not without ether or similiar. I am going to go and compare both setups today
 
I have to pump the throttle a lot more than 3 or 4 times to get them started after sitting for a week or two. I start pumping and when it kicks over I stop, this may be more like 10 or 12 times. I know the gas drained out of the carb.

It could be you need to pump the throttle a lot more.
 
bulletine said:
I have to pump the throttle a lot more than 3 or 4 times to get them started after sitting for a week or two. I start pumping and when it kicks over I stop, this may be more like 10 or 12 times. I know the gas drained out of the carb.

It could be you need to pump the throttle a lot more.
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I went down today and tried to start it again with no luck even pumping it appr. 7-10 times. Again put some ether in the carb and away it started and ran for 30 minutes. I am going to try again tomorrow and see after only 1 day if it starts. The other engine started with only 3 pumps of the throttle so something unusual going on. Any more recommendations are appreciated

Thanks
 
The accelerator pump is a good indicator if there is fuel in the bowl. Pump and watch the primaries. After two weeks, my edlebrocks need a lot of cranking.
 
some quadrajets are prone to leaking fuel from the two press in plugs located under the float bowl. there is a common fix available at auto repair stores that sell carb repair kits. separately sold....ask for the "well sponge". you only need to take the base plate of the carb off....the well sponge is about an inch square, and it is pretty obvious where it goes. it is a very easy install, and anyone that has a quadrajet should do this upgrade.

fuel seeps around these plugs on some carbs, and the sponge seals for some reason are not included in any rebuild kits. they are readily available.
 
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diver_dave said:
The accelerator pump is a good indicator if there is fuel in the bowl. Pump and watch the primaries. After two weeks, my edlebrocks need a lot of cranking.
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That is what is confusing me at this point, the throttle pump will not bring sufficient fuel to start the engine, once ether is applied it starts immediately and will run forever as normal even when the throttle is increased. So one would say that the carburetor is supplying sufficient fuel to make the engine run at any throttle level so why will fuel not be supplied at start up?? I have worked on these engines and carbs on muscle cars in the past and have never seen the unusual circumstances that are presented once these 454's are placed in a marine environment, 4 hrs boating equals 8 hours repairing
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So is the issue not enough fuel in the float bowl or the accelerator pump not working correctly? Lack of fuel in the bowl will prohibit the pump from working, as will a lot of sediment in the bowl for that matter. Unless you have rebuilt the carbs with a kit that has ethanol tolerant soft parts, you may want to consider doing that.

Regarding the need for the sponges, if you have a 170-series casting, the only reason the plugs would leak is if the casting has been damaged...The older 70-series castings are a different story and are at the root of the "legends" associated with those "leaks".

As far as unusual events, remember the marine engine room is significantly different than the engine compartment of a muscle car...when you factor in the change in the environment, most of the mystery will disappear.
 
makomark said:
So is the issue not enough fuel in the float bowl or the accelerator pump not working correctly? Lack of fuel in the bowl will prohibit the pump from working, as will a lot of sediment in the bowl for that matter. Unless you have rebuilt the carbs with a kit that has ethanol tolerant soft parts, you may want to consider doing that.

Regarding the need for the sponges, if you have a 170-series casting, the only reason the plugs would leak is if the casting has been damaged...The older 70-series castings are a different story and are at the root of the "legends" associated with those "leaks".

As far as unusual events, remember the marine engine room is significantly different than the engine compartment of a muscle car...when you factor in the change in the environment, most of the mystery will disappear.
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Thanks - if your referring to the fuel pump/accelerator pump its brand new, unless you are referring to another part I am not familiar with by that term? as far as the float ball it would seem logical that there is not enough fuel in the float bowl as if by pumping the accelerator the engine wont start without priming it with ether. Again once the engine starts with prime, it runs without incident so the mechanical fuel pump is working as it should.
 
contender31 said:
Thanks - if your referring to the fuel pump/accelerator pump its brand new, unless you are referring to another part I am not familiar with by that term? as far as the float ball it would seem logical that there is not enough fuel in the float bowl as if by pumping the accelerator the engine wont start without priming it with ether. Again once the engine starts with prime, it runs without incident so the mechanical fuel pump is working as it should.
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no sense of leaking or flooded fuel I would add regardless of before start or after
 
I think it was already suggested that when you have the problem, try checking the fuel level in the carb bowl by putting something like a narrow plastic cable tie wrap down through one of the vent pipes on the top of the carb. Compare what you see with the other engine. If there is adequate fuel in the bowl, hold open the choke butterfly so you can see down into the throat of the carb, and pump the throttle lever at the carb...or just push down on the top of the accelerator plunger ... to see if fuel is being sprayed into the carb. If the bowl appears to be empty, or near empty, then either crank the engine until there is fuel in the carb and retest the accelerator pump, or use the ether to start the engine, run for while and then shut it down, and retest for fuel being sprayed by the accelerator pump.

Also check your fuel water separator to make sure it is full before performing a cold start. If it is only partially full you may have a leak in the fuel line and air is getting pulled into the filter. The leak may allow air in but not leak fuel out.

My $.02 anyway.
 
Had a very interesting time locating the problem with my twin 454's.
found small inline back flow preventer incorporated into the fuel shutoff at the tanks. I say tanks because both had failed. It was not untill the second one failed that my problem became very apparrent. The failed back flow preventor allowed the fuel to travel back to the tanks making cold starts take considerably longer, once started they ran perfect! starting multiple times, next day... no problems.
changed out the shutoffs and badabing! Problem solved! Maybe it will help, hopefully!
 
Megabyte said:
Had a very interesting time locating the problem with my twin 454's.
found small inline back flow preventer incorporated into the fuel shutoff at the tanks. I say tanks because both had failed. It was not untill the second one failed that my problem became very apparrent. The failed back flow preventer allowed the fuel to travel back to the tanks making cold starts take considerably longer, once started they ran perfect! starting multiple times, next day... no problems.
changed out the shutoffs and badabing! Problem solved! Maybe it will help, hopefully!
Click to expand...

Never heard of a back flow preventer. They were probably what is usually called an anti-siphon valves which prevents fuel from siphoning out of the tank in case there is a leak or break in the line at a point lower than the highest level of fuel in the tank. But since these valves have a spring and ball inside them and need the suction of the fuel pump to open and allow the flow of fuel, they would normally be closed and also prevent any fuel from flowing back to the tank. They can get partially clogged and cause all sorts of grief. Worth removing and cleaning.

Erich
 
Even if the accelerator pump is new, it doesn't mean it is still working. When you pump the throttle at starting, does it spray fuel down the throat of the carb? If not bad accelerator pump, no fuel in bowl or air leak in the line that allows fuel to retreat. I once had a 1985 454 and the filter can at the engine had a pin hole leak in it and it behaved as you described.....I had to prime the carb in order to start and pull the fuel.
 
mabbott said:
Even if the accelerator pump is new, it doesn't mean it is still working. When you pump the throttle at starting, does it spray fuel down the throat of the carb? If not bad accelerator pump, no fuel in bowl or air leak in the line that allows fuel to retreat. I once had a 1985 454 and the filter can at the engine had a pin hole leak in it and it behaved as you described.....I had to prime the carb in order to start and pull the fuel.
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Ok after sitting for 2 days it started without incident, I did however check the inline fuel filter at the carb and realized the spring that is suppose to be installed on the carb side of the filter was installed on the line side thus making the filter somewhat useless. I Don't think this was a cause but glad I noticed it. I will continue to extend the times between starts and see if the problem re occurs. Note: I did just get new marine fuel delivered 2 days ago as I believe the old fuel from last year was either ethanol or had lost its octane level.
 
kimcrwbr1 said:
Maybe check the temperature of both engines at the intake manifold shortly after you turn them off after a good run. If there is a big rise in the tamp after it is turned off it could be causing the fuel to boil off more than the other one. If there is a big rise in temp the block could use a good flush? I am assumeing it is raw water cooled.
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Thanks no closed cooling raw water pump, both engines have new exhaust complete with exhaust manifolds and raw water pumps - ka-ching:mad:
 
So the recently refurbished carb had it internal filter assembled incorrectly...I'd keep that fact in mind as you continue to troubleshoot
 
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