Advice please!! '75 starting problems

Johnd

Regular user
I have a '75 convertible, L48 engine, original carb & mechanical fuel pump. When left standing for a few days, I find I need to pump the throttle numerous times to get enough fuel up to enable it to start & idle without stalling. Is this normal? Would an auxiliary electric pump wired independently be the answer just to pull fuel up?
Thanks in advance, John
 

Oneball

CCCUK Member
I’d check that fuel isn’t draining back to the tank due to a faulty mech fuel pump.

What carb have you got?
 

Forrest Gump

CCCUK regional rep
Hi john
It could be the choke isn’t working properly. The fuel pump must be getting fuel to the carb or it wouldn’t run at all.
 

Corvetteville

CCCUK Member
This is a long, but very useful thread from Lars on the Corvette Forum in the US.
 

Roscobbc

Moderator
Common issue whether Holley or Quadrajet - fuel drain back to tank (as carb is higher than tank) In my view not such a bad thing. Why you ask? - Simply turning the engine over for a few seconds without it firing gives the oil pump ample chance to 'prime'the engine with oil before it fires - thus preventing excess engine wear and potentially that 'death rattle' start-up from the big ends and other internal components.
Racers will often have a starter switch and a separate ignition switch for that very reason - i.e don't hit the ignition until you see oil pressure showing on the gauge. Just a thought.....
 

kentvette

CCCUK Member
John, as has been said, it's not uncommon, indeed, common, for Q-Jet cars to take a bit of "encouragement" to start. I've mentioned this in another post recently, but our carb was set up by a friend, a chap who was THE man in So Cal for 30 odd years, but from cold, ie after a few days, it still requires at least two full throttle pumps and then will crank for exactly 5 seconds before it fires. Apart from ensuring the choke pull-off valve was working (it wasn't originally!) my buddy spent a while adjusting the choke to ensure that it was fully shut when the engine was cold, but came off when it was warm. It is also important to get the "Fast Idle" adjustment just right. The engine should run at about 13 - 1400 rpm when initially started from cold, a blip on the throttle after a few minutes to allow it to warm through should then bring it down to about 1000 rpm (900 in D)

As always, the advice from Lars is good, but you may just find that some attention to adjustments works! If you have the Haynes manual, the section on the carb is actually pretty accurate and useful.

Lars makes a good point re Ethanol fuels, by the way. Aside from the manifest ignorance about their environmental benefits, they should be avoided like the plague if you run an older car. Given that it is almost impossible to do that, I have now begun adding Millers EPS, as all fuel over here is at least 5% Ethanol. Miller EPS has been proven to aleviate almost all of Ethanol's harmful effects.
 

Daytona Vette

Well-known user
The inline fuel filter just before the carb should be a one way non return filter

Another reason for difficulty in starting after standing for a few weeks could be due to engine wear and low compression after the oil has drained down - I had it on a Volvo with worn lifters, always spark, air and fuel but after standing for 3 -4 weeks would turn well, but refused to fire quickly
 

curious bystander

CCCUK Member
As Stephen says they don't start like a modern engine.
After years of experimentation my method of starting after several days (or longer) lay up - floor the throttle twice, then crank the engine for two short (3-4 second) bursts - without touching the accelerator peddle - then leave for 3 or 4 minutes. Will then start instantly
Start pumping the peddle while cranking I find floods the engine.
 

Johnd

Regular user
Thank you all for your advice & opinions. Not being mechanically minded I think I'll get GS Autos in Collier Row Romford to check it over for me unless anyone can recommend anywhere else within fairly easy reach of Brentwood.
 
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