I have a 1987 Firebird with a 350 SBC crate motor and 1406 Edelbrock carb on a Weiand intake. The car runs fine, but is extremely difficult to restart after it has gotten up to operating temperature and then sat for more than a few minutes. I think it is vapor lock. Will installing an electric fuel pump (such as a Holley Red Pump) make it easier to start when hot?

I know Edelbrocks have a siphoning issue and they're more susceptible to vapor lock than other carbs, but I've had this issue when using a Holley 4160 as well.

Here are the things I've already done:

- switched to a vented fuel cap to prevent a vacuum from building in the tank

- installed a 0.5" carb spacer (the biggest that fits)

- moved the fuel line away from the engine and exhaust.

- verified timing and spark plug gap.

- upgraded radiator

If an electric pump will help, any tips for where or how to mount it? I'm thinking of mounting it to the spare tire hump, and tapping into the existing hardline.

Thanks

 

It's probably not "vapor lock".

Worst thing you can do is "assume" some ancient legend that probably doesn't apply to your car.

First thing to do would be to figure out why it's hard to start. Is it rich? lean? flooding? etc. What do you see when you look down the throttles in the middle of an episode? Does it take forever to crank, then when it finally does, does it blow out big clouds of black smoke?

 

It takes forever to crank. I've tried a variety of strategies with the gas peddle, the most succesful is pumping it once or twice, then holding it to the floor while cranking. When it does catch, it struggles to stay running. I have to keep it at part throttle for a minute or so before it comes up to it's normal idle speed and stays running. The fuel line is usually dry when I start, but even when there is fuel in the line it has a hard time catching.

I haven't noticed significant smoke when it catches. The accelerator nozzle is working. I've set the idle circuit and electric choke based on the edelbrock manual. I've gone through a few different jet and metering rod settings, it's never had an effect on the starting issue, good or bad.

 

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Have had the same problem with my 87 camaro. Super annoying. I never did figure it out. Just been living with it. I got a eddy 1405 on mine. Basically same as yours but manual choke.

I first thought heat in fuel lines so I put heat wrap where it ran close to exhaust. No change.

Tried the wooden clothes pin method another member here said worked great for him. No change

Then thought maybe a electric pump might force fuel threw in case it's still vapor locking. If yours car is factory carbureted like mine then you should have a in tank electric helper pump (gm only did that in 1987 I believe). I dropped my tank and replaced mine with a new one from Napa. Then wired it to a toggle because it never worked to begin with. Flipped it on and got 2-3psi to the carb. It helped prime it when it's been sitting for weeks but when it's hot and been sitting for 10 minutes as yours. No change.

I figured the carb was the problem when it gets hot. Got a new Holley style carb but haven't tried it yet to see if that changes anything.

I'll be watching this one. Hopefully you guys figure it out because I've been dealing with it for years

 

i never looked down the throttle blades though. Ill have to do that next time I get it out. What should we be looking for sofakingdom

 

Just, to see what's in there.

Is it bone dry? Is there fuel running everywhere? Does it look normal, with a small amount of fuel all only in the right places and a normal-looking pump shot if you give it one? The cause and cure in each of those situations would be entirely different. Just kinda generally see what's going on, instead of jumping to some kind of conclusion.

Next time it does it, as soon as it becomes apparent that it's happening, just get out and look.

 

I'm interested to see how this turns out, too. My 1407 does exactly the same thing. I attributed it to heat soak and haven't pursued it any further.

 

an 87 LG4 should have come with an in-tank electric pump that helped feed the block mounted pump. as would a former fuel injected motor.

 

When having trouble, what happens if you push the pedal to the floor and hold it?

 

LOOK DOWN IN THE THROTTLES when you're having the problem.

You'll see one of 3 things: too much fuel, no/inadequate fuel, about the right amount of fuel.

What you need to do depends on WHAT YOU SEE WHEN YOU LOOK DOWN IN THE CARB while your car is enjoying the problem.

Nothing else matters... yet.

 

The fuel line on my 1982 was almost touching the header. I unbolted the clamp and moved them up and over the frame rail area and my problem went away.

I also had the Edelbrock 1407 at the time.

- moved the fuel line away from the engine and exhaust.

 

Hi guys, Mike here, I've been away for a while. Now have a 1987 Iroc-z with 5.0 HO that was TPI until I just swapped to Cyclone polished intake and a 650 DP Proform w/mechanical sec. I have the same problem once it gets hot and sits for a bit. I just noticed my front bowl becomes empty after it sits, so I'm guessing a total flood issue. To restart requires a couple pumps and hold it to the floor. Plenty of black smoke once it cranks and takes a minute to smooth out...

 

I plan to pull the front bowl tomorrow, among other things, and see if I can figure out why it's draining empty after it sits. The rear bowl is fine. I only assume at this point it's draining into the intake, instead of the fuel line, will find out tomorrow.

 

Change your air filter while your at it. those triangle ones are foam and can be a fire hazard if the car backfires. Also I would recommend replacing that plastic fuel filter with a steel one which wont melt or get brittle and crack.

 

Your problem is most likely, the fuel getting hot from the block's heat while sitting in the pump, building up pressure, forcing its way past the needle valve, and exploding into vapor when it suddenly reaches atmospheric (reduced) pressure. Just like shaking up a Coke bottle and popping the top. EXACTLY like, in fact.

The solution is to insulate the fuel pump from the block.

https://www.cantonracingproducts.com...&category=8510

 

Hard starts when hot just make me think that the fuel is evaporating in the carb or the pump(because hot engine, no air movement, etc).

I see two options - continue to fight with the block pump, insulate it from the block

or install a pusher pump (holley red or blue) and get rid of the heat soak issue altogether.