Engine/Transmission (1998.5 - 2002) Spillover valve ??????

[Bobalos]

What is it?

Where is it?

What does it do?



Also, is there a check valve in/near the tank that has an affect on Fuel pressure?



thanks

Bob

 

[B.G. Smith]

There is an overflow valve in the return line from the VP-44 injection pump. It is also a check valve, it is supposed to open at 14psig and be closed below 10psig. It is actually in the stud that goes through the banjo fitting that secures the return line to the VP-44. The manual states "if the valve is stuck open, fuel drainage from the injection pump mcould cause low engine power. Hard starting may also result".

 

[gottorq33]

would this cause an 0216 code

 

[Bobalos]

Is there a check valve or something back by the tank that could affect the lift pump presure?



Here is the deal:



I replaced the fuel filter & lift pump maybe a year ago. this was right after I put my gauges (Fuel Pres, EGT & Boost) in. it ran GREAT for the last year. 2 days ago I noticed that @ cruise (40 to 50 MPH, the fuel pressure would run about 10 to 11 Lbs. if I gave it a little gas or the load on the motor went up a bit (small hill) the fuel pressure would drop down to 6 PSI. But if I hammered on it it would stay right @ 8 1/2 or 9. Also the idle pressure is 12 to 13 which is down about a Lb from what it was.



Good is:

Idle 12 1/2 to 13

WOT 9 (VERY stable)

Cruise @ 70 MPH 12 or 12 1/2



Bad is:

Idle 12 to 12 1/2 (not very stable)

WOT 8 1/2 to 9 (moves around)

Cruise @ 70 MPH 11 1/2 to 12

Cruise @ 40 MPH 9 to 10 but drops to 6 or 7 for a few seconds.



Any ideas? I was told to fill the tank up full (its about 1/2 tank right now), because there is a check valve (or something) back @ the tank that could be causing this & filling it up will tell me.



thanks

bob

 

[Bobalos]

BTW, the FP Gauge is on the output of the filter canister. I am going to swap the filter tonight (although its new, & I dont ever run the tank to <1/4 tank. I drained the water trap into a pan the other day & there was not any water in it.



Tanx again

Bob

 

[B.G. Smith]

Low fuel supply pressure or restriction in fuel supply can set the code as well as problems with the VP-44. I am not aware of any other check valves at the tank, there is an inlet screen on the fuel pickup at the tank. The higher the fuel level, the less the lift pump has to pull the fuel resulting in higher output pressure although I doubt you would be able to determine that small of an increase. Yoyr pressures seem ok but since it is fluctuating it would be worth watching. bg

 

[Bobalos]

Right on BG, thanks a bunch. there is something deffinately wrong here. the FP has been ROCK SOLID since I put the new lift pump in it & now its ... ... ... ... just wrong.



any other ideas?



thanks guys.

Bob

 

[Bobalos]

OK, So when I got home I checked my service Manual & there is a Roll Over valve in the top of the tank where the sending unit is & as BG said, there is the overflow valve in the return side of the VP that sends gas back to the tank if the lift pump pressure is too high.



I took the Overflow valve out of the VP & its simply a spring loaded check valve. I blew air though it & checked it out & it appeared to Not be stuck in either direction. Took it for a drive & same thing.



I then figured I ought to swap out the $45 filter that my wife just bought today & what-do-ya-know. its fixed.



So all that worry over the stupid Fuel Filter. interesting, to me is that its almost 10,000 miles since I changed it. I guess when Dodge says to change the filter @ 10K, they REALLY mean it.



thanks again gents.

Bob

 

[Bobalos]

UPDATE:



after about a week of driving everything seemed OK. However, it started acting up again. I called the folks @ Jannetty (GREAT guys I must say) & talked with them about it & the one guy there suggested that I take the Elect Gauge off of it (Pillar mounted Auto meter elect), & put a mech gauge in it & see if its the gauge that is doing it, & that this did not sound like a FP problem.



I bought a mech 15Lb gauge, hooked it to the same line that I had hooked to the sending unit for the AM gauge & taped it to the windshield (as if I did not get enough stares with the desiel, LOL)



I put 1-1/2 tanks of fuel through the truck & did not have a lick of problems with it. the FP is fine.



I contacted AM via email & told them what was happening. the one sentence reply I got from them was "Is this a desiel". I said "yes" & here is his reply:



If it is a diesel, then it is very possible that the sender is failed/failing. This happens due to quick, high pressure spikes in the fuel system. During replacement of the sender, I recommend that you install a pressure snubber available from a company called Chemiquip. Order # 12S which is a 1/8npt male & female stainless steel pressure snubber. You may contact them at 201-868-4445 or 201-868-4446. Please send me your name and address and I will send you a sending unit. I strongly recommend

the snubber to protect against future failure.

Thank you.

Cory

Tech/Service



Food for thought.

Bob

 

[rweis]

Some guys use a 18" grease gun hose as a buffer for the fp gauge. One person used a needle valve on the end of the grease gun hose and turned the needle valve all but off to minimize the pressure spikes.



I have a bypass regulator on my lp and I see no pressure spikes as the fuel has a place to go if there are spikes coming back down the supply line. The bypass regulator is set to 12 psi.



A lot of guys move the lp to the frame so it can push rather than suck. There are all most as many variations to the fuel system as there are guys on TDR.



Just some ideas,



Bob Weis

 

[Bobalos]

thanks Bob,



I think that I am going to relocate my lift pump with one of those Practical Desiel Solutions kits. it simply makes more sense to have an electric pump push rather than pull.



Im on the fence about the gauge. its pretty crummy that Auto Meter does not say anything about it or provide a solution to this. heck if they offered something for this application, I would have bought it up front & not had the worry. I about lost my lunch when I saw the fuel pressure dropping to 5. 5 & 6. 0 Lbs.



Anywho, I guess I have to get over it & get on with a solution.



thanks



Bob

 

[SHobbs]

Is this the same valve that if there was a red cap on it, it needed to be removed. It was supposed to be removed upon installation of the tank. If so a friend of mine didn't know about it, his tank was starting to collapse in on itself from the vacuum created in the tank. He was having problems with acceleration, L. P, and starting. I removed it and all his problems disappeared. Sounded like the tank let out a sigh of relief when I pulled the cap off.

 

[Bobalos]

@ the risk of beating a dead horse. I got my "snubber" in the mail yesterday & I also got the new sending unit from AM on Monday. one thing I noticed was that this is not the same sending unit that I got with the Gauge. not sure if its the new part number that comes with all the gauges now, or if its a "special" one for the Diesel applications. either way I put them together & hooked it all up & it works *****en. the gauge is a LOT more stable. its a little slow to respond now, but it doesnt really need to be fast, just tell me when the Lift pump has died.



for anyone that cares, I put together a fast web page last night, its @ http://www.r71camaro.homestead.com/TrckSendingUnit.html



& here is a quick shot of the snubber #ad




& one of the snubber & the sending unit all ready to go into the truck

#ad




Bob