EFI Accumulator Fuel Pump Problem?

[Killer Frogs]

'73 Bronco with a 5.0 from a 2000 Explorer. The engine continues to pop and surge. It does it mainly when accelerating or under load, going up hill. I'm running two fuel pumps with an accumulator between the two pumps. I have a gauge on the fuel line and at idle it is fine at about 63 psi.

My suspicion is that the high pressure fuel pump is struggling. I'm thinking of figuring how to mount my phone on the underside of the hood to keep an "eye" on the fuel pressure gauge while driving. Garry, the "EFI guy" said he has seen problems with the accumulator. The attached photo shows the plumbing I'm using.

Possible problems I'm thinking are:

• Is the high pressure pump not getting enough fuel? If so why?
• If the high pressure pump is not working wouldn't it just stop pumping? Or is ther some other way it might be failing?
• Other Ideas? I know there is not a vacuum leak.

Thanks

 

[cag33]

I had the same problem. High pressure pump would suck accumulator dry under acceleration and fill it up at idle. I replaced low pressure pump with a higher GPH low pressure pump and all has been well.

 

[cag33]

One other thing, I used the W/H accumulator that has a return line on that also.

 

[Killer Frogs]

I had the same problem. High pressure pump would suck accumulator dry under acceleration and fill it up at idle. I replaced low pressure pump with a higher GPH low pressure pump and all has been well.

Thanks a TON! ;D Hopefully this will cure the problem. I bought my accumulator from BC Broncos. They have a large and small option, I chose the large one and have this problem, glad I didn't choose the small one!

How many GPH is the fuel pump you are using to get fuel from the tank to the accumulator?

 

[NYLES]

why run 2 pumps? my opinion of that accumulator is mine has been thrown out bout 5 years ago. 1 hp pump one return will fix it fer good

 

[Timmy390]

I run an external HP pump mounted on the cross member just above the stock sending unit and have had no issues thus far.

I don't have a bunch of miles on my rig since going EFI but the miles I do have, EFI has been flawless.

Tim

 

[AZ69EB]

I've been running a clear plastic filter, then EFI pump, and finally an EFI filter for the past 5 or 6 years. Most people in Arizona who ran the accumulator had issues with vapor locking due to heat. I added a small plate close to the outlet of the stock tank. My pump is a few inches lower than the outlet. No problems what so ever. The EFI pump is the aero 2000. My fuel pressure is set at 44lbs via pressure gauge. I added a few pounds due to a little lean condition above 4500 rpm on dyno. It took care of the problem. Stock 19 lb injectors should be around 38 to 42 lbs fuel pressure. If it was mine, I would ditch the exta pump & the accumulator. Good luck

 

[Timmy390]

I've been running a clear plastic filter, then EFI pump, and finally an EFI filter for the past 5 or 6 years. Most people in Arizona who ran the accumulator had issues with vapor locking due to heat. I added a small plate close to the outlet of the stock tank. My pump is a few inches lower than the outlet. No problems what so ever. The EFI pump is the aero 2000. My fuel pressure is set at 44lbs via pressure gauge. I added a few pounds due to a little lean condition above 4500 rpm on dyno. It took care of the problem. Stock 19 lb injectors should be around 38 to 42 lbs fuel pressure. If it was mine, I would ditch the exta pump & the accumulator. Good luck

Same setup as me. Clear filter before an Aero 2000 and EFI filter after.

Tim

 

[Killer Frogs]

thanks, anyone want to buy a lightly used accumulator and low pressure pump!

 

[chuzie]

My experience with that style accumulator is air supplied from the return gets trapped, builds up and causes the HP to lose prime. I ended up removing my return line from the accumulator and routed it directly to the tank then capped the port in the accumulator. All is well and runs great.

Sure, this will slightly reduce my run time should the tank go dry, but not enough to matter in my opinion.

 

[pcf_mark]

Don;t let me lead you down a crazy path but...I've considered taking an electric oil pressure sensor/gauge combo and screwing it into the fuel pressure port. Take out the schrader valve and screw it right in. Then you have electric fuel pressure gage for diagnosis.

I would never do it with a mechanical gauge that could be a fire hazard but the electric ones are perfect..

 

[garberz]

why run 2 pumps? my opinion of that accumulator is mine has been thrown out bout 5 years ago. I hp pump one return will fix it fer good

I'm with Nyles on this. I have the lower pressure fuel system, but a simple frame mounted pump near the rear tank has served me well for several years now.

Mark

 

[jw0747]

Toss the accumulator and run a straight fuel line between the pumps and it should work.

 

[garberz]

Toss the accumulator and run a straight fuel line between the pumps and it should work.

Why would you run both pumps?

 

[ntsqd]

What is the fuel pressure at the engine when it lays over?
What is the fuel pressure at the outlet of the LP pump when it lays over?

Until you know both of those numbers you don't know which pump is the problem.

Most low pressure pumps are designed to be dead-headed and only flow the amount of fuel needed for some max HP production. EFI use requires enough volume for not only HP production but also some return volume. So if your LP pump doesn't flow enough it could be starving the system.

If the LP pressure stays constant, but the HP pump pressure drops it may not be the pump. It could be a partially plugged accumulator filter. Water in the fuel can partially plug the filter and you likely won't be able to tell visually.

 

[welndmn]

63 PSI is WAY too much.
I'd check for a blocked return line.
You should be 35-45 PSI

 

[Viperwolf1]

63 PSI is WAY too much.
I'd check for a blocked return line.
You should be 35-45 PSI

65 psi is correct pressure for a returnless rail explorer system.

 

[Timmy390]

Per his drawing, he's running a return line......

Tim

 

[Viperwolf1]

Per his drawing, he's running a return line......

Tim

Yes, but he's also using the small injectors from the returnless rail system which want to see 65 psi.

 

[welndmn]

To me this seems like this might be a return issue.
I'm not sure how to plumb in a return line on a return less system.
Are you using a Mustang or 1997-1999 explorer fuel rail? The returnless ones just had a damper on it.
I'm not sure where your issue is, but the mixing and matching of return and retrunless parts could be part of it.