Bad float or fuel pump on ex-EFI?
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From: Davenport, IA
Bad float or fuel pump on ex-EFI?
I've got a 87 F150 that I threw a 79' carb on and an electric fuel pump (among other things). Seems the bowl is overflowing. Are there in-tank fuel pumps on the EFI's too. Wondering if I've got too much pressure going to the carb or if I didn't get the float right when I did the carb rebuild. Think I had a problem before though...
Don't recall what the pressure rating was on the e-fuel pump - maybe 8-10. What should the max pressure be?
Don't recall what the pressure rating was on the e-fuel pump - maybe 8-10. What should the max pressure be?
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From: Saddle Brook United State
The following answer is based on the assumption that you changed an EFI setup to a carb.If you are using the original in tank electric pump that supplied the injectors and no pressure regulator, you are WAY over pressure as the pump puts out 60 plus PSI. The carb should use around 5-6 psi. Its a wonder you don't have gas spurting from every opening on the carb, like Old Faithful the geyser. Your
post states it was an ex EFI. Why did you go from an EFI setup to a 79 carb? it's sort of like shootin yerself in the foot. That is also a computer engine set up for Injection, it aught to run real good(not) with a carb.
stractor
post states it was an ex EFI. Why did you go from an EFI setup to a 79 carb? it's sort of like shootin yerself in the foot. That is also a computer engine set up for Injection, it aught to run real good(not) with a carb.
stractor
Last edited by stractor; Nov 30, 2004 at 12:46 AM.
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From: Davenport, IA
Thanks for the info.
Wow, 60 psi for the in-tank fuel pump. I disconnected the fuel pump on the rail - I figured it would be high pressure, but I figured if there were in-tank fuel pumps, they would be low pressure ones. Hmmm...now I wonder why I'm not blowing gas everywhere! Guess I'll have to fix that eventually, till then I'll just keep on drivin' it.
Also didn't know there was a big difference between the 87 efi'd and the earlier carb'd motor mechanical parts. I realize the head has extra air intake ports (don't recall what for), but is the valve train really much different? Can't imagine what would be changed on the low end. Seems to time alright.
Wow, 60 psi for the in-tank fuel pump. I disconnected the fuel pump on the rail - I figured it would be high pressure, but I figured if there were in-tank fuel pumps, they would be low pressure ones. Hmmm...now I wonder why I'm not blowing gas everywhere! Guess I'll have to fix that eventually, till then I'll just keep on drivin' it.
Also didn't know there was a big difference between the 87 efi'd and the earlier carb'd motor mechanical parts. I realize the head has extra air intake ports (don't recall what for), but is the valve train really much different? Can't imagine what would be changed on the low end. Seems to time alright.
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From your first post, looks like you installed an electric fuel pump for a carburetor, after you disconnected the efi fuel pump on the frame rail. Your right, there is another fuel pump in the tank, the earlier efi 4.9 used a low pressure pump in the tank and high pressure on the frame rail, disconnect the intank pump and you should be good. You shouldn't be any where near 60 psi with the low psi pump, but it cannot be helping anything either. Some people opt to run a fuel pressure regulator on the low psi pump but since you already have the carb pump, that would probably be a waste.
For what its worth, the later efi 4.9 only had one intank pump.
There isn't much difference between the carbed and efi. The holes in the ports, that you mentioned, are air injection for smog equipment. The efi head has a heard shaped chamber simillar to the 302 e6's, a good design for building low end tq. Seems the general idea is, the efi head can handle more timing than the carb head, so you may wanna play around with that some.
Good luck
For what its worth, the later efi 4.9 only had one intank pump.
There isn't much difference between the carbed and efi. The holes in the ports, that you mentioned, are air injection for smog equipment. The efi head has a heard shaped chamber simillar to the 302 e6's, a good design for building low end tq. Seems the general idea is, the efi head can handle more timing than the carb head, so you may wanna play around with that some.
Good luck
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From: Davenport, IA
Originally Posted by jwtaylor
...disconnect the intank pump and you should be good.
If I need to remove both tank pumps (duel tanks), I'm thinking I might be better off pulling my cheapy add on fuel pump and putting on the regulator. It's a cost to work comparison situation.
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Some people simply disconnect the wiring and go, some disconnect the wiring and find it impossible to draw fuel using a mechanical or carbed electric fuel pump, through the existing pumps. I cannot explain why that is the case but I know it happens.
I can see the benefits of going with a regulator vs removing the pump, if that happens in your case.
Good luck, lemme know what you end up doing
I can see the benefits of going with a regulator vs removing the pump, if that happens in your case.
Good luck, lemme know what you end up doing
