Engine/Transmission (1998.5 - 2002) BOMBed fuel pickup, now pumping foam (HELP!)

[Vaughn MacKenzie]

I just installed 1/2" plumbing from inside the tank pickup to the filter canister. I put a Carter HP 100gph pump in front of the tank and don't have the stock pump. I added a 1/2" tube inside the pickup assembly because the stock one looks so restrictive, barely a quarter of an inch.



I got it all together tonight and it started easily enough after running a couple key cycles and priming it. I let it idle a couple minutes and had great fuel pressure, right at 15psi. Took off for a test drive and strangely the pressure began to drop immediately and continued downard to about 4psi. I stopped and sat there letting it idle and it gradullay worked its way back to about 12. But the moment I started driving it nosedived again. I headed back to the house and then it continued downward to 0, then it began to sputter and miss, and then it conked out.



I cycled the key and the pressure came back up to 15psi. I cycled the key repeatedly but after trying for half an hour it refused to start. My neighbor came along and towed me home with is Ford Escort :{ :{ :{



I have about 1/8 tank of fuel in the tank. It seems the pickup is getting a lot of air. It is about 1/3" off the bottom of the tank. The problem I fear is, the tank pickup is a complicated contraption designed to hold fuel and keep the pickup in constant prime when the tank is low to prevent air from being drawn up. Unfortunately I couldn't install the larger tube without defeating this. My fear is I am now screwed and will have to buy another pickup assembly for big $$$ and my whole project that I've been busting my butt on for the last 3 nights is all for naught



I'm wondering if anyone has any ideas. Tomorrow I will fill the tank at least half way and see if the problem subsides. If it does I know it's a pickup problem. If not, then the next thought is the new pump is defective.



Thanks,

Vaughn

 

[BIG BOB]

That is a bummer! I hope it work when you fill it up to 1/2 full. If that works do you think you will make it to Diesel Thunder?



I've been working with Mallory on my setup. They want me to install a by-pass regulator (which they gave me, no charge! Thank's Mallory!) They don't want the pump actuated by the stock pump wiring, they want it to pump continously when the key is on. I'll post on it later. I was think about this setup after the last pump went out at 6300 miles. It kind of funny, they were thinking the same thing. The logic in this new setup seem right. I'll post after I get it installed.



Good luck Vaughn, hope to see you at Diesel Thunder!

 

[kaffine krazed]

Another way to check for air. Get a section of clear tubing and install it between the fuel tank and the fuel pump. Since you are only loosing fuel pressure when driving shake the truck while watching the line and see if it pulls in air.

 

[Devildog]

I wonder.....

If you fuel level is low enough and your pump volume is high enough that you could be creating a vortex at the pickup and pulling in air that way, hhmmmm..... Keep us posted.

 

[Devildog]

OR. . could have a pin hole in the pump assembly, or suction side of the fuel line some where. Are your clamps tight enough?

 

[SnoKing]

You guys should get a job at DC, with all your engineering ability you could resolve all kinds of problems for them. SNOKING

 

[Roger rodbolt]

Vaughan,

I suspect that your system will work fine with more fuel in the tank. If your fuel pickup is one third inch off the tank botton air will be intrained because of fuel slosh (unporting) in our LONG tanks. I've got a similar system in my '98 and see fuel pressure pulse with less then a quarter tank and stop and go driving. The factory fuel pickup sits on the tank bottom and I'll change mine to do the same the next time I drop the tank. Is the 1/2 inch tube that you installed in your tank rigid pipe? If not you will need a heavy weight on the end to keep it straight down. Good luck. Larry

 

[willyslover]

Vaughn... . get me a e-mail as to your findings... got a "spare" pick-up here in the old rigs tank, that is out of the rig and behind the house. . so could be in transit very quickly

only issue is that I'm going to Napa for 3 days and then on to Eureka [Ca. ] for about a week...

 

[Vaughn MacKenzie]

UPDATE

Well I've been messing around all AM and haven't really gotten any closer to a solution.



I added several gallons of fuel to bring it to just under 1/2 tank. Got it started, drove it around, same problem. . . pressure nosedives. Acts like it is starving for fuel. I don't see how it can be a pickup problem. I was extremely careful when setting it up that it was 1/3" off the bottom.



Next I unbolted the bed and double-checked fittings at top of pickup assy. , all good and tight like I expected. When putting this all together I was very careful about integrity.



Although it acts like it's sucking air I cannot comprehend how it can be any fault with the pickup assembly. Next thought is somehow the Edelbrock prefilter is sucking air, or the pump is bad.



I removed the line from the canister and added a long length of hose and fed it into a clear container to check for air. I cycled the key to run the pump and only got a few microscopic air bubbles. Not nearly enough to cause a loss in prime. Then I went and drove around the block, it only takes about 300 feet of driving for the pressure to drop to 0, and then quickly pulled into the garage and hooked up my hose and checked for air. It did blow air but only the amount drawn in when the injection pump sucked the fuel out of the line. After a couple moments it was solid fuel.



So I guess it may be the POS Carter pump. What do you think? If so I'm probably screwed $80 since I bought it about 9 months ago.



Vaughn

 

[willyslover]

Vaughn... not sure where your checking the fuel from. . before or after the filter... did you pick-up water off the bottom or some trash. . check out your filter if you have not done so

 

[Vaughn MacKenzie]

Gary, that part looks OK. We checked the filter in front of the lift pump and it was clean as a whiste



Well it's the lift pump. POS Carter. Ordering another one and should be back on the road next week.



PNWRadar drove all the way here and gave me a hand, we tore off the bed and took it all apart and came to the conclusion it was the LP.



Thanks so much everyone



Vaughn

 

[Vaughn MacKenzie]

It's STILL DEAD

ANOTHER new lift pump did NOTHING to help. 9 Days and Counting with a Dead Truck in the Garage



:mad;





So somehow even with half a tank the thing is sucking up enough air to lose prime even though when I check it with clear tubing there is no air pumped out.



What could it be????????? Electrical problem??? Tried 2 different relays. 2 dead pumps in a row???????



I'm at a loss for an explaination but I have decided to completely DE-BOMB the entire thing and go back to what I had: stock setup with lift pump at tank with stock, unmodified, restrictive pickup assembly.



Thanks for helping me out Gary, looking forward to getting back on the road.



40+ hours of frustration, bustin' my hiney, wasting a lot of $$,



ALL FOR NOTHING

 

[Texas Diesel]

Re: It's STILL DEAD

Originally posted by Vaughn MacKenzie

ANOTHER new lift pump did NOTHING to help. 9 Days and Counting with a Dead Truck in the Garage

40+ hours of frustration, bustin' my hiney, wasting a lot of $$,



ALL FOR NOTHING

AND getting towed by a Phord Escort

 

[Roger rodbolt]

Vaughan,

Sorry that you are still having trouble. A couple of thoughts... ... . your VP44 alone, will pull a vacumn on the fuel lines and run the truck just fine at low power settings without any lift pump, so if you are depriming I suspect that the system is drawing air somewhere. Very small chance that the lift pump could be causing a restriction (not running at all?).



I would pressure test the new lines (system) from the fuel canister to the end of the pickup tube. You could cap one end and install a schroeder valve and guage on the other. Pump the sytem up to 15psi or so and leave it for several hours... . it should lose absolutely no pressure. If it does you can use soap bubbles in a spray bottle to check for leaks. Some would say the Carter lift pump would need to be removed from the system to pressure test as the check valve in the pump could cause a restriction. I'm unsure about a new pump but on older pumps the checks valve don't seal well enough cause problem during a pressure leak down test.



Did you use theaded iron pipe for your pickup tube? Is it sealed by orings where it goes through the tank or threaded fitting? I will email you a phone number if I can be of assistance, hang in there as you can fix this!!! Larry

 

[Devildog]

This may be a crazy question but,

Are you sure you have the line coming from your fuel tank to the "inlet" side of the pusher pump, and the line going to the engine on the "outlet" side of the pusher pump. I have seen this before and creates the symptoms your describing... That pump can be mounted either way on the bracket.

 

[15w40]

One other thought. Be sure the wiring to the pump is not reversed. I accidentally hooked a lift pump up, and swapped the power leads when I was testing it. It ran backwards and instead of making pressure it created a small vacuum at the output port.

 

[HVAC]

Vaughn, did you get some more fuel in the tank? Like I mentioned, I don't let my tank get to 1/8 cause I see the pressure bouncing around.



Like the guy said, polarity is important, check that. And the pump is clearly marked inlet/outlet, check that. Then go back over the connections.



Because the problem manifests itself while your driving, I'd have to think the source is within the tank. That's the only thing that changes when you drive. The fuel sloshes around

 

[John Berger]

fuel sloshing

That's what I was thinking. When you sit idle everything seems to work fine. Have you tried running with a full tank?

 

[Vaughn MacKenzie]

Thanks for tips

Thank you guys for all the suggestions. Nowell I have 1/2 of tank of fuel right now so I would think that would be enough. I will go add more (if I can make it to the station 1 block away and fill it up).



Devildog I did make sure I connected the inlet/outlet sides properly, hose from tank is connected to "Inlet" and hose from pump to engine connected to "outlet. "



Polarity: I tested this before I installed the pump at the beginning of the project and wired it up. I connected a hose to the inlet side of the pump and stuck it in fuel and activated it with a battery I have in the garage. I checked the polarity of the power from the truck's wiring to verify positive & negative. I know the polarity is correct because it does pump fuel and has great fuel pressure at idle, and pumps it out in large quantities when I cycle the key and run a hose from the filter canister to a container.



My next thought is to remove the 4" diameter filter screen in the bottom of the tank fuel is drawn through before pulled up by the pickup tube and see if that makes any difference. IT seems to flow good but maybe it isn't.



Thanks again everyone,



Vaughn

 

[Rockcrusher]

Did you try removing the fuel tank cap and give it a run?