Engine/Transmission (1998.5 - 2002) 2 pusher pumps in 3 weeks! What can be wrong?

[DLausche]

I had bought a Carter 4601Hp and Racor 645 filter about a year ago. Finally got to put them on about a month ago now. Both are mounted back by the tank to push fuel rather than pull. Gave away the stock LP which was still doing fairly well. Also put in -8an fittings and 1/2" lines from new LP to stock filter canister and to the VP (which is also fairly new). Fired it up for the first time and was quite happy with the FP from my new setup (13/14 most of the time). But, 3 weeks later my FP started reading 6 max. I could pull it down to 0 with less than half of go pedal. I figured I must have got a bad pump and it had sat on my shelf for a year and was not under warranty anymore. So, I bought a new pump (4601HP) from Summit. Put it in a bit over a week ago. FP was back up to a pretty solid 13/14 right away so I figured the pump had fixed my problem. Drove to work and back the next day no problems. Fired it up the next morning and I have the same 6psi fuel pressure issue. Can pull it to 0 easily. So, now I figure something else is up. Changed the stock fuel filter. Still 6psi. Change the Racor (10 micron) filter. Still 6psi. Bypass the Racor completely, still 6psi. This 6psi max is with the engine NOT running - just bumped the starter like priming the pump. Bought another gauge and hooked up right to stock filter canister. Both FP gauges are the same (6 max, engine not running). Hooked pusher pump directly to battery to rule out electrical issue - same 6psi. Then thinking something in the VP is allowing fuel to pass and not hold pressure. So, I bump the start again and pinch of the 1/2" hose from filter to VP. You guessed it - 6psi max. Everything is leading me to think I have another bad Carter pump. But, the two have reacted EXACTLY the same as each other. One lasted 3 weeks and the other a little over 1 day. What have I done wrong? Is a 10 micron filter plus the stock filter just too much for one of these Carter pumps and I am burning them out? Also thought about a blockage of some sort in the tank pickup, but wouldn't I be able to build almost regular pressure without the engine running since there is virtually zero fuel flow actually needed without engine running?



Should I do a different brand pump like a Holley?



This is really frustrating!



Thanks for any input you guys can give me.

-Deon

 

[RACE427]

Fuel Pickup tube

Have you checked the fuel pickup tube, screen in the tank for restrictions, clogging with gunk? You could try some compressed air down the fuel line into the tank to try and dislodge any sludge, sediment buildup. Just a thought!

 

[DLausche]

OK, just tried that. Easy enough to do now. Put 90psi back down pickup line with tank cap off. Could hear lots of rumbling in the tank!!! Must be clear now. Hooked back up and bled air out of line. Have ~6psi again. 0 with just a bit of go pedal. Still have Racor disconnected. FP before and after stock filter is about . 75 psi diff.

 

[mgoncalves]

When my 4601 stranded me, I found out that the screen inside was much, much finer than the screen inside our stock lp's. My guess is the super fine screen is to much restriction especially in cold weather, and simply overheats the motor of the pump. That is just my guess. My 4601 worked decent for 2 months, and as the weather got a little colder, the pressure would drop. When it finally died it could make 5 psi with the engine off, but could barely keep positive pressure at idle. I limped it about 2 miles that way, thank god we were close to a town.



Matt

 

[Gary - K7GLD]

Usually, low PSI in a good pump is caused by low supply voltage, or a restriction to flow - wonder how hard it would be to run the pump off the truck thru a separate fuel supply and line with an adjustable restriction, IE, pinch the output line to verify max PSI capability OFF the truck?



Other than that, are you running straight NO. 2 diesel, or some mix of Biodiesel? I suspect SOME alternate fuel types might cause these pumps operational problems due to the fuel actually circulating thru the motor itself, possibly creating brush to commutator issues...

 

[Turboman]

Its the Carter pumps, They are JUNK! I played the same game back in July. My first 4601 lasted over a year, 2nd about 3 months, 3rd 6 days. Luckily each I wouls alternate buying from Summit and Jegs. I always kept a spare, when one would quit, send it back for credit, I finally bit the bullet for a FASS and returned the last Carter for credit so I guess the Carters never costed me anything. No FP is always 16-18psi.

 

[RACE427]

Haisley Machine

We installed a Haisley Machine pickup tube on our shop class Dodge here at our school. The Haisley pickup tube is 1/2 diameter and offers no restriction to fuel flow. I do not know if this will solve your problem but it cannot hurt to have all the fuel flow you might ever need.

 

[mhenon]

We installed a Haisley Machine pickup tube on our shop class Dodge here at our school. The Haisley pickup tube is 1/2 diameter and offers no restriction to fuel flow. I do not know if this will solve your problem but it cannot hurt to have all the fuel flow you might ever need.

Where did you get that pick-up tube (is there a web-site?) and how tough is the install?

Mike

 

[DLausche]

Usually, low PSI in a good pump is caused by low supply voltage, or a restriction to flow - wonder how hard it would be to run the pump off the truck thru a separate fuel supply and line with an adjustable restriction, IE, pinch the output line to verify max PSI capability OFF the truck?



Other than that, are you running straight NO. 2 diesel, or some mix of Biodiesel? I suspect SOME alternate fuel types might cause these pumps operational problems due to the fuel actually circulating thru the motor itself, possibly creating brush to commutator issues...

Straight # 2 diesel here. You thoughts Gary are along the same line as mine. What does the pump put out with no restrictions and no fuel draw (i. e. engine off). I have not bench tested like your idea. But, I do not see how the lines could possibly be plugged up. I blew out the pickup line to tank last night. Same result. Line to from tank to pump MUST be clear. The fuel from tank will just run out if I let it.



My thought is even if there was a restriction of some sort in my lines, then that should not matter too much when the engine is not running as there is no fuel drawdown from the engine, etc.



What I've done so far... I've verified 6 PSI reading is correct via a 2nd gauge on filter housing. Replaced both filter elements with new. I've tested with line to VP pinched closed to make sure the VP isn't bleading pressure internally somehow. I've removed Racor filter from the picture altogether. I've hooked the Carter directly to battery to rule out electical issue. All times I get 6psi with engine off.



I have resigned myself to the fact that I have another bad pump. I'm sure Summit will replace it.



So, does anyone know if 2 filters is just too much for one of these Carter pumps? I'm pulling through a 10 micron Racor and pushing through the stock filter. Would I be better off with a Holley blue or black rather than trying another Carter?



Is is possible these aftermarket Carter pumps are not compatible with Diesel of any kind?

 

[Gary - K7GLD]

"Is is possible these aftermarket Carter pumps are not compatible with Diesel of any kind?"



YUP - I read about tests you had already done, and the outboard test I suggested is about all that's left to verify actual pump problems.



The stock LP on these trucks is a Carter - and I use a Carter 4600 as my pusher pump with no problems, and I go thru both the stock fuel filter, as well as a Frantz sub-micron filter - no problems at all in 40,000 miles and 3+ years operation...



These pumps WILL cavitate and lose PSI if sufficient restrictions or operation up at max pressure is maintained - and in tests I have run, the ONLY way normal operation will be restored is to shut the engine down and restart. If your PSI seems OK at first startup, then drops, try shutting the engine down and restarting to see if normal PSI returns for a bit - if so, your problem might be cavitation.

 

[DLausche]

OK, I am curious now about this cavitation idea. If I have only 6psi without starting then the cavitation is not the issue? But, if I had not noticed that I had caviation, and ran the truck/pump that way could that be the reason for both of these pumps going out so soon? Does the Racor filter before the pusher pump in my setup contribute to cavitation? I didn't think filter before or after would make any difference but am not sure now.



-Deon

 

[RACE427]

If I remember their web address is www.haisleymachine.com real nice people to deal with and the pickup tube is not difficult to install. . in fact they sell a complete auxilary fuel system for the Dodge. Hope this help!! Good Luck

 

[Gary - K7GLD]

OK, I am curious now about this cavitation idea. If I have only 6psi without starting then the cavitation is not the issue? But, if I had not noticed that I had caviation, and ran the truck/pump that way could that be the reason for both of these pumps going out so soon? Does the Racor filter before the pusher pump in my setup contribute to cavitation? I didn't think filter before or after would make any difference but am not sure now.



-Deon

I don't know that cavitation in these pumps will do any serious damage to the pump itself, it's what happens downstream that's the biggest issue. And yeah, I'd give serious consideration to putting the Racor AFTER the pump - there's already a fuel filter inside the tank to protect the pump from random debris...

 

[rweis]

Not saying good, bad, or indifferent, but I run the RACOR 690 T(10 micron) before the lp. I had a bypass after the lp set at 12psi and had a VP die at 53k. I might have killed the VP with the bypass maybe not allowing enough fuel to the VP. Pressures were always good 12psi measured before and after the OEM ff.



My Vp failure was typical of a heat problem failure. Ran fine around town. Push it hard and hot and it would "dead pedal" 0216.



Just my experience, FWIW



Bob Weis



I run a RASP now. Lots of fuel, lots of psi.

 

[Huff N Puff]

Any kind of restriction on the suction side of the pump will cause cavitation

OK, I am curious now about this cavitation idea. If I have only 6psi without starting then the cavitation is not the issue? But, if I had not noticed that I had caviation, and ran the truck/pump that way could that be the reason for both of these pumps going out so soon? Does the Racor filter before the pusher pump in my setup contribute to cavitation? I didn't think filter before or after would make any difference but am not sure now.



-Deon

The other reasons for cavitation are air leaks. The stock fuel module is very restrictive and is prone to air leaks. Mopar has updated the fuel module with an in tank pump. This will eliminate all restrictions on the suction side and eliminate a possible air leaks,they have also provided a relay to power up this pump which will eliminate any voltage problems. Cavitation is LESS likely to occur when the pressure on the high side is up. It is MORE likely to occur when the pressure on the high side drops because that is when the pump is moving the most fuel and is creating a vacuum on the suction side.

 

[EDembowski]

I too have been having a problem with the Carter 4601HP pump. Initially, I relocated it to just in front of the tank with a Purolator pre-filter. I have gone through several pumps, none of them lasting more than 3 months. The latest one I installed, I bypassed the pre-filter. My pressure is higher on this pump than any of the others that failed, 15-17psi. I tested each pump to verify what is going wrong, of the 4 pumps I've gone through, the common thread seems to be that the internal bypass relief valve is sticking open. All the pumps run, turning vanes are in good shape, and the screens are clear, just won't produce any pressure. If bypassing the pre-filter doesn't work, I think switching to a Holley blue would be the best bet considering they are rebuildable, including the bypass relief, which seems to the problem I've had 4 times so far.

 

[DLausche]

I too have been having a problem with the Carter 4601HP pump. Initially, I relocated it to just in front of the tank with a Purolator pre-filter. I have gone through several pumps, none of them lasting more than 3 months. The latest one I installed, I bypassed the pre-filter. My pressure is higher on this pump than any of the others that failed, 15-17psi. I tested each pump to verify what is going wrong, of the 4 pumps I've gone through, the common thread seems to be that the internal bypass relief valve is sticking open. All the pumps run, turning vanes are in good shape, and the screens are clear, just won't produce any pressure. If bypassing the pre-filter doesn't work, I think switching to a Holley blue would be the best bet considering they are rebuildable, including the bypass relief, which seems to the problem I've had 4 times so far.

Now that is very interesting info. This could explain why both of mine that have failed are acting identically. Is there any way to fix the bypass relief valve so it does not stick open anymore? Like fix the bypass valve so it cannot open anymore?



My Holley black pump just arrived today and will be going on tonight. Not sure yet if I should put the Racor filter back on or not. I might run a while without it and then put it on and see what the difference is psi wise.



-Deon

 

[RAndrae]

SIMPLE-- get a fass or air dog.

 

[EDembowski]

No!

The only part of the pump you can get to is the vanes. You would have to destroy the housing to get to the bypass. The only other way would be to block off the bypass with JB Weld.

Good luck with your Holley, I bet you get much better results, I would still lose the pre-filter though. Too much restriction on the suction side of the pump. Besides, the way the slide vanes work on these pumps, they would not be affected by most debris that would be inside the tank. Be sure to keep at least your stock filter in use. These pumps are designed to push, not pull.

 

[DLausche]

Holley black installed

I just finished installing the Holley Black pump. Have psi that fluctuates between 9 and 10 now at idle. Sits steady at 9 with engine off. Have not taken it yet for a spin around the block. I have to admit that I did expect a bit more psi out of this pump. Hookup was easy. The mounting bracket for Carter and the Holley pump had compatible bolt spacing and in/out fitting height with relation to mounting bolts was similar.



Tomorrow we will see how it works on the road.



-Deon