Electric Fuel Pump

shfletch

I have a fairly healthy 360 built and put in my 77 cj7. Currently I am using a holley electric fuel pump with the internal regulator that flows 97 gph. The carburator is an Edelbrock 650 thunder series off road type. On flat ground I can run through the gears reving the engine to 6500 rpm with no issues. I built the jeep for running the sand dunes and when climbing a hill where the engine runs at high rpm for 5 to 10 seconds anything over 5000 rpm it starts missing like its running out of fuel. I don't think it's the hill angle since it runs up to 5000 very smooth. What pump volumes are others of you running? Do you think switching to a 130 - 150 gph pump help?

ironman_gq

might be a problem with the float adjustment of the carb. at an angle its probably not letting enough fuel into the bowls.

Goose

Yea you might check and see if the springs loaded needle and seat are in place, If I rememebr right he floats are rear hung on that one..

shfletch

Thats a good idea, I will take the carb off and measure the fuel volume in the bowls at different angles while trying to fill through the inlet tube to see when the floats try to shut off the flow. I know of some guys that have experimented with different spacers and cutting them in a slight wedge to offset the angle some.

Goose

Yea the ultimate solution is fuel injection..Course If your like me and broke.. Ummm maybe not so much. The other thing I would check is the grounds from battery to block and block to frame.. If your twisting her out of shape a bit, And you have a weak ground the electronic ignition may be breaking up a bit.. Just something to think about.

shfletch

Fuel Injection - I submitted it to the home finance department and it came back DENIED.....like I expected it to go through anyway. I was very careful and setup good solid ground straps from the battery to the engine and then to the frame and back to the body, so I don't feel that is my problem. Also, it is not getting twisted much, as I am shooting up sand dunes that are fairly flat, just long and steep that require extended periods of high rpm. As soon as it starts missing, I can back out of it just 200 - 300 rpm and it smooths out. I am going to pull the carb and start measuring the floats, maybe I will give the techs at edelbrock a call and see if they have run into this before.

Holeshot

Running the bowls dry does not cause a miss. Just makes it run out of gas, and I think we all know what that "baaaaaaaaw" is like.

Just because your fuel pump is capable of flowing 97gph doesn't mean that it is getting anywhere near that much to the carb inlet. You need to install a fuel pressure guage out by your windshield wiper & monitor the pressure at the carb inlet.

Please inform us of exactly which fuel pump you are using, most REAL pumps have an external regulator to install near the carb, how can an internal regged pump know how much is making it to the carb? Any tight bends, restrictions, restrictive filter, etc., will make the pump "think" it has reached full pressure or the bowls are full!!! You are probably making enough power to move up to .500" fuel line as well.

shfletch

Thats more on the track I was on when I started this topic, I was thinking about moving up to a larger fuel line and also a higher volume pump with an external regulator up by the carb so I get full pressure all the way through up to the reg. Any preferences for filters, I have one back by the tank and one inline edelbrock on the carb.

ironman_gq

it could be ignition related.if 200-300 rpm's fixes it you might be getting crossfire in your dizzy or could have a high speed miss on one of your plugs. If you rule out fuel flow go through your ignition next.

shfletch

Right now I feel very strongly that it is fuel related, especially since on flat ground I can run it well over 5000 rpm with no issues. Given the time of the year, I think I will just make a new pump, regulator and larger fuel line my xmas present from wife and kids. I will get it on and then we have a 5 day trip on the 27th to the dunes, so I will have plenty of time to experiment out there if this does not work. Thanks for the input.

Holeshot

I haven't used an AFB since the late '70s, but I'd be suspecting those metering needles & the springs that regulate them (or the float springs). Is this a fairly new carb?? I'd always use a Holley over anything but maybe a Demon, myself.

mika01

shfletch wrote
Given the time of the year, I think I will just make a new pump, regulator and larger fuel line my xmas present. I will get it on and then we have a 5 day trip on the 27th to the dunes, so I will have plenty of time to experiment out there if this does not work.

Wow you were right I do have a very similar problem! Could you keep me informed on what works for you to solve this issue? I'd appreciate it.

shfletch

The carb is new out of the box from edelbrock. Back in the late 70's I had a cj with the 304 that I tried using a holley on and never had any luck. If I even pointed it at a hill it would sputter, flood and die out. I know many other's that had also tried with similiar results. I remember back then most people off road were using the AFB or a quadrajet. I used an AFB and had good luck, but was never pushing the 304 nearly as hard as I am this engine. Holeshot, I think you have a very good point with the regulator being up at the carburator and having full pressure all the way up the line and then regulate it down at the last point before the carb. I would have put the reg down by the tank and when you mentioned that, the light bulb suddenly went on, duh.... This takes me back to my old college years in my flow dynamics class. The old regulators that I remember, had that adjustable knob on them that always leaked through the diaphram if you actually tried to adjust it. Do you know are the newer ones any better for leakage, I would assume they have corrected that by now.

Holeshot

I hope your X-mas present solves your problem, but, don't be surprised if you end up wishing Santa would have completed the fuel system with a Holley 3310. :smilebox:

Holeshot

There are some great ones now, & the NHRA, IHRA, & NASCAR rules protect us by forcing good products to market. I'm partial to Holley, but BGI & Mallory are good as well.