fuel check valve

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fuel check valve

Postby captainben on Mon Nov 23, 2009 7:16 pm

My fuel check valve is shot, meaning long cranks to get the engine started, even with new electronic fuel pump. I've been told that a replacement part is no longer made. Is there a check valve from another make of car that will work with th 1979 Fiat 124 Spider?
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Re: fuel check valve

Postby majicwrench on Mon Nov 23, 2009 9:46 pm

Forgive my ignorance, FI or carb??
FI pumps, at least on all the cars I see, have a built in check valve, system should hold pressure.
Most of your cheapy low pressure pumps do not have a check vavle..
Mechanical pumps have a check valve built in, it often gets debris under it, and then needs cleaning.
What say ye, FI or carb??
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Re: fuel check valve

Postby captainben on Mon Nov 23, 2009 10:01 pm

Sorry about that. It has a carb. When the car sits, the gas drains out of the carb. That's why it takes all the cranking to get it started.
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Re: fuel check valve

Postby So Cal Mark on Mon Nov 23, 2009 10:59 pm

probably has a leaking accelerator pump diaphragm
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allisonsautomotive.com gear reduction starters for the 124, 131, X1/9, 850 Distributorless ignitions for 124, 131, X 1/9, Monza wheels
X1/9, 131, 124 Spider exhaust system, http://www.fiat500speed.com
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Re: fuel check valve

Postby captainben on Tue Nov 24, 2009 12:53 pm

The carb has been rebuilt, so that's not it. Both of the major Fiat supply places have told me that it's the check valve and I can't get one. One guy laughed and said me and few hundred others would like to find one, so it must be a relatively common problem. I was told that a check valve from a Volkswagen Beatle might work. Anyone know anything about that?
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Re: fuel check valve

Postby majicwrench on Tue Nov 24, 2009 1:41 pm

There is a check valve built into the mechanical fuel pump.
If indeed fuel is draining from carb, it has to drain SOMEWHERE, where is it going?? It cannot get sucked back up into the fuel inlet line.
It is possible for the fuel in the fuel line to drain back to tank somewhat, this is why mechanical fuel pump has check valve.
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Re: fuel check valve

Postby mbouse on Tue Nov 24, 2009 1:50 pm

hey ben, i have the same trouble... the float bowl empties after a few days and takes what seems forever to prime the system back up, and my carb is fairly new. it could be that yours is as mark suggests, but i doubt it.

i have heard others with the same issue have resolved that by turning the electric fuel pump on and waiting a few seconds before attempting to crank their engine. since the electric pump is an aftermarket add on/replacement for your mechanical pump on your '79... are you able to do this, turn the pump on for 45 seconds before cranking the engine?

you certainly could throw in any fuel check valve in the feed line between the firewall and the carb to see if it fixes your issue. i don't think that Fiats are that picky that they cannot use a V W check valve...

be thankful that the factory check valve is missing from under your hood. according to Chris Obert, this part was safety recalled in the mid-80's and not all cars were caught in that recall. the solution to the leaking check valve (which was causing engine fires) was to yank the part from the car and replace with straight rubber fuel line. somehow, my '80 was not recalled, and my valve failed by just shutting down...no fire for me.
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Re: fuel check valve

Postby captainben on Tue Nov 24, 2009 2:21 pm

Thanks for both replies. I do have the electronic fuel pump, a replacement because I still had the problem with the mechanical fuel pump. I've been running the electronic fuel pump for 10 seconds. I will try a longer shot. I finally found an illustration of the check valve in a shop manual. I'll have to go looking for it. It seems that some enterprising fellow would have come up with a replacement part.
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Re: fuel check valve

Postby mbouse on Tue Nov 24, 2009 2:31 pm

Jon Logan put an electric pump on his '79 because he didn't like the embarassment of having the engine crank so long while he waited for the mechanical system to refill.

he is the one that inspired my suggestion about waiting for a while to allow the lines and float bowl to fill.
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Re: fuel check valve

Postby captainben on Tue Nov 24, 2009 2:37 pm

I just found a universal check valve on line. I've ordered one ($14). When it is installed, I'll give you an update.
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Re: fuel check valve

Postby carl55 on Tue Nov 24, 2009 10:23 pm

Where did you find the check valve?

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Re: fuel check valve

Postby captainben on Wed Nov 25, 2009 12:10 am

I found it on e-bay. Try jbass 19508@bellsouth.net.
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Re: fuel check valve

Postby So Cal Mark on Wed Nov 25, 2009 12:44 am

as majicwrench wrote, the fuel can't siphon from the float bowl back through the needle and seat into the fuel line. Adding a check valve won't have any effect on the float bowl draining. Since the base and center section are all one piece, you either have a leaking accelerator pump or a cracked carburetor. Just because your carb is "rebuilt" doesn't mean much. I've seen accelerator pumps fail within a few days of exposure to our reformulated fuel, and more commonly, warped pump covers that allow some seepage.
Whichever Fiat supply houses gave you that info should quit having sales people give advice, they're obviously more versed in sitting in front of a computer than actually fixing a car
Mark Allison
allisonsautomotive.com gear reduction starters for the 124, 131, X1/9, 850 Distributorless ignitions for 124, 131, X 1/9, Monza wheels
X1/9, 131, 124 Spider exhaust system, http://www.fiat500speed.com
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Re: fuel check valve

Postby captainben on Wed Nov 25, 2009 11:07 am

My mechanic who rebuilt the carb insists that it is not the carb that is the problem but getting gas to the carb. He has about 40 years of experience working on old cars, including two other Fiat spiders I owned, two MGBs, and an Alfa spider. He has rebuilt several carbs for me successfully, including a couple of S.U.s. I tend to believe what he says. I'll try the check valve first, as the car had a long crank time before and after the carb rebuild. It's a cheap fix. If that doesn't work, then I will look for a new carb, no such a cheap fix.
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Re: fuel check valve

Postby mbouse on Wed Nov 25, 2009 11:46 am

Ben, let me know how it works... i am convinced that my carb is functioning properly too, and i don't want to swap out my current fuel pump at this time.
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