elec. fuel pump problems!!???

[little hoss 86]

ok guys i got little hoss running now and it takes gas fine and seems to run ok but it won't ldle well at all if i set up the idle it seem to be fine but when i shut it off it runs backwards,if i set it down its like it wants to load up. i have a 10 psi pump could that be too big and at an idle it just gets too much fuel? under a load it fine runs like a champ.... help!! if i cant get it right soon i'm going to 302 auto!!!

 

[Mark_88]

The carbs can only take about 7PSI pressure from a pump and if you go over that you risk blowing out the (needle) carb...not sure if that is what is causing the idle problem though...

I had to make several adjustments to my carb to get it to idle right regardless of using the electric pump or the manual one that was standard. The idle can also be adjusted through the distributor through slight rotation...counter-clockwise tends to increase idle and clockwise reduces it and I used that more than the screw on the throttle...there is that 'sweet spot' that makes everything good...but finding it takes a few tries...

What is your current idle RPMs, and what is the recommended RPMs for idle...I know mine was around 800...but I've never had a tach so I always set it by ear...may have been a bit high most of the time but that was preferred to lugging the engine.

 

[little hoss 86]

not sure on the idle rpm i'm the same way just by ear, tonight i got a fuel psi regulator at the parts store, so tommrow i am going to try about 4psi and then go up from there, i would say that if i go to low on the psi that it will run out of gas in a load, i'll check back and let you know. also on the timing did you go straight up or 4degrees advanced?

 

[Mark_88]

I set the timing according to the marks on the gears, even though I do have an adjustable timing gear...then I adjusted the air/fuel mixture and turned the distributor till it idled smoothly and there was acceleration without stutter...

I might add that the vacuum hose on the distributor should go to a connection on top of the manifold...I swapped this out from a post on here years ago as I was using a lower intake connector that didn't have the right vacuum to advance timing or maintain smooth idle...

Was the engine running properly at any time or has this been an ongoing problem?

And if you've got a regulator I'd start out around 5 or 6 psi...4 might be a bit too low and you may introduce other problems at that pressure...

 

[little hoss 86]

well it ran like a champ till christmas eve last year and it dumped on me so i put this new on together and now its just test and tune,, i have the vac advance on the base of the carb.i done away whith all other vac, ports and had a carb spacer plate made to replace the egr set up because my new motor came from a 93 so i used the header frome it w/no set up for egr, i think the only vac line i need is the vac advance right? where did you set your air/fuel? i went all the way in and then backed it out a turn and a quarter... i'll go whith 6psi to start today and let you know how that comes out....

 

[Mark_88]

Sounds like my truck...93 shorty header...but it does have an EGR inlet...it's on the inside of mine close to the block, but I was using that until recently...

I think I did the same thing with the air/fuel...turned in all the way and then backed off about 1¼ turns...I have the Motorcraft 5200 carb and there is actually another setting on the side near the valve cover...I had that turned all the way in too and that was not supposed to be like that...didn't realize it was a vent until I pulled the carb off and had a good look at it...

I just checked my fuel pump and it is rated at 5.5 psi but when I tested it the reading was 7 psi...it's not adjustable and I don't have a regulator.

Using the vac at the base of the carb may be ok but I'm not sure...I always go to the tree where the brake booster connects since there are two small outlets there that work with the vac advance tube without patching...the idle problem could also be vac leak so you might want to have another look for broken or missing hoses

 

[little hoss 86]

ok well the regulator didn;t work it ran great but if i held a steady speed it sucked the bowl dry,51/2 psi is as high as it goes so i took it off and hooked the pump up straight again and it seems to be fine

it ldles fine if i just lightly tap the gas,but the problem is when i shut it off it wants to run backwards, if i punch the pedel and get it to idle back down it don't do that quiet as bad... now its not ideling way high by any means but it is high enough if i shut it off like that it will run backwards. also my pump says 7-10 so it may be fine after all..

 

[Mark_88]

I'm not quite sure what you mean by 'running backwards'...do you mean just run-on like it won't shut down completely or is there something else that it's doing out of the ordinary?

Run-on can be caused by a number of things and is also called "dieseling"...and you can find out more about it from this link...

http://www.mgaguru.com/mgtech/engine/ro101.htm

 

[little hoss 86]

dieseling..i have heard this term before thats what i have... i think.. you shut it off and it rattels and wheezes out the carb and sometimes i get a small back fire.. but if the idle goes way down or i put it up aginst the clutch and shut it off it don't do it then.

 

[Mark_88]

Well if that's what's wrong it may be an easy fix...one of the items on that page was the plugs are too hot...not sure if it was you that posted about putting in a higher capacity ignition system that could be causing the problem if the plugs are not rated for the higher heat...so changing the plugs with a higher rated heat plug would help...

Otherwise, I'd suggest go through the list of items...maybe try a higher octane gas if the plugs are OK...or adjust the carb to run a bit richer...

 

[Kenneth S]

What carb are you running?

 

[Byrd]

The big block in my 67' does that if I don't put high enough octaine gas in it... I'd check those plugs first like Mark said too.
Another thing that happend to me was that I had a blown diaphram in my carb which led to flooding. It just gave me a very rough idle and stalling but it seems reasonable that It could be on its way out and giving you some issues... Just a thought


-Byrd

 

[little hoss 86]

i am running the stock carter 1bbl, i don't recall which one it is,but let me ask this..the whole story is in my other thred about switching to efi but the high point is i took out a 2.0 used a 2.3 out of a 93 used a 2.3 head off a 86 or 87 ran my 2.o carb and intake...now is there enough differeance there from 2.0 to 2.3 that i shoud be using the webber carb that came whith my 2.3 head i bought?

 

[Kenneth S]

The one barrel should be ok on the 2.3, on the Holley 2 barrel on my 2.3 the idle is inconsistent, I added a second return spring on the carb on my carb and still have some idle inconsistencies, what I started doing when I have to let off the throttle to come to a stop instead of slowly letting off the peddal I just quickly slip my foot off the peddal allowing the carb "snap" shut so it will idle the same. Chances are the bore for the throttle shaft is loose in the carb thus causing the butterfly not to able to sit properly in the carb body, or the the carb to intake surfaces are not completely flat thus distorting the carb body slightly and not letting the butterflt to sit right. Try the letting it "snap" shut method and see what happens.

 

[Byrd]

Might try running the webber too... cant hurt to try... rebuilds arent expensive either so that is another option for you aswell... Hard to deduce exactly what it is whithout being there but thats why you have so many minds on here that all think from different angles. This very much sounds fuel related to me and there are only so many things that can fail in the fuel delivery system... Note that this is a little dangerous and I might catch flack for saying this but spraying a slow stream of deep-creep or WD40 down the carb to see if it will level out on its own will tell you for sure that its fuel related just don't get crazy with it because it can rev up on you or backfire/sneaze and ignite what you've sprayed...

Id try the carb swap or rebuild first though.

-Byrd