EFI Fuel Deliver Problem

[CupricReki]

I have the efi fuel delivery system that utilizes the low pressure pump that feeds the accumulator that feeds the high pressure pump for my efi system. For some unknown reason on a warmish day (Or a long day of wheeling), the high pressure pump stops getting fuel.

I have a very high gph low pressure pump mounted as low as possible in the back, and isolated the fuel lines from any heat source i can find. It still makes no difference at all. One thing i noticed is that when the HP pump stops getting fuel i can kink the return line and that seems to do the trick for a bit. But after a while it stops pumping again. I tried to put a pressure regulator on the return line thinking the accumulator wasnt collecting enough fuel but that only seemed to make the intervals in between the pump going dry increase.

Im Completely at a loss as to what to do.

 

[Viperwolf1]

I had the same problem. I was using a 6-port Pollack valve between the tanks and the LP pump. It seemed to me that the LP pump couldn't flow as much volume as the HP pump when hot. Or it could have been vapor lock in the Pollack valve. I reconfigured the system to use LP pumps directly out of each tank pushing through the valve. I haven't had the problem occur since then. The pump I added was the Carter 4070 on the main tank. The LP pump I used previously was moved to the aux tank. I figured the Carter pump would be better at running for long periods of time on the big tank.

 

[CupricReki]

Well I have don't have any valves or restrictions between the LP pump and the HP pump, just the Accumulator. I was thinking about this a bit more and would it cause problems that my HP pump is above the accumulator and return line? Also I reinstalled the mech pump in line between the LP and the Accumulator hoping this would help. It helped when my main tank ran out and the LP pump needed to be primed, but that was it. Also it didn't seem to make it worst.

 

[jim02]

I saw many threads on simular sounding trouble here in CO after I started to have trouble with my set up(same as yours) having the same issue.
The threads I found say this is common in CO and to move to a intake pump to resolve the issue.
Since I only have a single 12 gal tank, I am getting a BC Bronco 23 gal tank with a in-tank pump next month myself. I need larger fuel capacity anyway.

 

[CupricReki]

Just got off the phone with a friend with a very similar setup and a very similar problem, he said he just got rid of the accumulator all together and never had any troubles with it ever again. So this is the net step, ill see how it goes and let you guys know. Thanks a lot for the input though.

 

[hmh800]

Hey Cupri-
Please let us know how you make out with this issue. I live in Eagle and am about to intall the same setup (dual tanks, dual pumps, etc.). I had a 5.0 in a CJ7 before this rig, with one internal Mustang pump, and never had any issues. I'm curious to see how you resolve this!

 

[CupricReki]

Ya for sure, I'm a full time student with a part time job, so i don't get a lot of time to work on it. But I'll try and get it done asap and let you know!

 

[zeeman1]

if the high pressure pump was above the return line that came off the accumulator then wouldn't the gas being pumped to the accumulator return to the tank before it went up to the HP pump? I would put the return line exit from the accumulator higher than the inlet on the HP pump and see if that does the trick.

 

[ej77eb]

Any success?

I have the same issue with the same set-up you describe. Today on the trail whenever we stopped, if I shut the engine off, it would struggle to restart with the heat soak. I put ice on the fuel line between the hp pump and fuel rail which seemed to help restart quicker. At the end of day it quit on the road back to my trailer. Kind of lost power, stumbled... "dieseled" some and quit.

ej

 

[SnwMnkys]

I just had fuel delivery problems this last week with my EFI. It felt like the motor was starving for fuel, and occasionally I would get a wierd noise out of my HP pump. I ended up removing my LP pump and my fuel filter, and moved my fuel filter AFTER the pump instead of before it. Seems to be running tons better now.

 

[Greg_B]

I have been running the HP pump only for around 10 years and have never had a fuel problem. I dont have a LP pump at all... I have used dual tanks and a pollack valve with the pump mounted to the frame under the passenger side. I run a filter at each tank and one after the pump.

I worried about it not pulling fuel but it has yet to let me down.

But I dont live in CO... seem like everyone that has fuel problems live in a higher altitude.

Greg

 

[Viperwolf1]

I just had fuel delivery problems this last week with my EFI. It felt like the motor was starving for fuel, and occasionally I would get a wierd noise out of my HP pump. I ended up removing my LP pump and my fuel filter, and moved my fuel filter AFTER the pump instead of before it. Seems to be running tons better now.

That weird noise was your HP pump starving for fuel. Bad idea to move the filter, it'll shorten the pump life. Might be better to move the HP pump closer to the tank.

 

[SnwMnkys]

That weird noise was your HP pump starving for fuel. Bad idea to move the filter, it'll shorten the pump life. Might be better to move the HP pump closer to the tank.

I plan on it, I was just trying to diagnose a problem. Ive got Summit Racing screw on type resevoir filter that will hopefully act like a small accumulator im going to try.

 

[DirtDonk]

What brand of accumulator are you using CupricReki? Is it store-bought or home-built? Nothing wrong with either type of course, but I just ran across one what was using a filter housing and did not have the pickup tube running to the bottom of the tank. So, in effect, it really was not an accumulator to my way of understanding.

Could you have the wrong cap on your filler too? If it's sealing completely, and you don't have your venting routed properly, could it simply be starving for fuel because it can't pull hard enough?

Just a couple of thoughts.

Paul

 

[Steve83]

Frank's had a lot of fuel problems when I was trying to keep the stock '88 reservoir/valve. But since I converted to electric valves & a stock reservoir only, it runs perfectly.



You should have a sock, but not a "filter", in the tank. The only "filter" should be between the HP pump & the fuel rail.

 

[av bronco]

Try bypassing the accumlater.

 

[CupricReki]

Well i just went ahead and removed the damn accumulator, took it to Moab right after and didn't have a single problem what so ever! Well besides destroying my spider gears .

 

[roundhouse]

I used to run a low pres and a hi pressure pump, till the lp pump dies and I bypassed it.

During that time I had the same problem as you, I solved it by installing a power steering cooler in the return line to the tank.

I now tun only a HP pump wit a clear filter before and a EFI filter between the pump and injectors.

The filter between the tank and pump catches a LOT of garbage.
You do need a filter between the tank & pump, and with a clear one you can see the trash.

 

[CupricReki]

I definitely have a filter between the pump and tank, i would never think of getting rid of one completely! But the accumulator definitely caused way more problems then it solved for sure.