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Prime-Loc Setup On 24V ISB Engines Can Cause Injection Pump Failure!!!

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Evan A. Beck

#ad
Hey guys... #ad


I know you may not like to hear this, but the Prime-Loc system on 24V ISB trucks could cause injection pump failure.

Here's why:

The fuel lines Prime-Loc supplies with the kit are far too small. Take a look at the fittings on the ends, and you will see that they are VERY small, about a 1/8" passage for fuel to go through. The small lines and added hose are just asking too much for the little lift pump. It has to suck fuel from the tank, then push it through the Prime-Loc maze of hoses, and then through some banjo bolts, and finally to the injection pump.

After doing pressure tests on a couple of trucks, we found the Prime-Loc system takes away a HUGE precentage of fuel pressure, and delivers (at most) only a couple pounds of pressure to the injection pump. Not good at all, especially because the VP44 is lubed and cooled by diesel fuel. ABout 70-75% of the fuel supplied to the VP44 is returned to the tank, and if it doesn't get enough fuel (both in pressure and volume), the pump will overheat and fail. One truck in our shop, a '99 to be exact, did have an injection pump destoyed due to low fuel pressure caused by restriction of fuel in the Prime-Loc.

So my advice to you guys with the Prime-Loc is to test your fuel pressure ASAP. Especially you guys with modified engines.

ACCEPTABLE FUEL PRESSURE:

While cranking, the pressure should be between 5-7 psi, according to Dodge specs. With the engine running, fuel pressure should be a minimum of 10 psi, according to Dodge specs. If the pressures test below this with the Prime-Loc on there, remove the Prime-Loc, and test it again. If it still tests low, you may need a new lift pump. If your pressures are higher than the figures mentioned above, great. #ad


If the fuel pressure is low with the Prime-Loc installed,a nd is OK with the stock filter setup, I would suggest calling Prime-Loc and informing them you are having a fuel pressure problem.

Also, get your overflow valve checked as well. It should be opening at 14-16 psi. Overflow valves can malfunction by either sticking open, or opening too soon. So be sure and check your overflow valve!

Bottom line...

Get your fuel pressure tested! It may save you an injection pump!!!

Be sure to post your fuel pressure test results here, I am VERY interesting in seeing what your pressures are.

BOMBED #ad

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Evan A. Beck "NW PUNK"
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'01 2500HD 4x2 QC, 139" WB, 6-speed, ETH, SLT... yadda yadda yadda... 25,769 miles since 4/26/00!
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Check out NW PUNK for more info! #ad
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[This message has been edited by Evan A. Beck (edited 11-14-2000). ]
 
Evan, thanks for the heads up! It surprises me PrimeLoc would market something like this with such restrictive lines. John's gonna Sh**!

Do you get the Summit Catalog? I saw a new Perma Cool fuel filter that is supposed to filter to 3 microns, flow plenty for our applications, and separates water. Check the "New Products" section in the Christmas catalog (Santa with Hotrod).

As you see I never made it by the Power Shop Friday. Camping trip didn't happen. I will be over Dec 10th weekend so may stop by then.

BTW I took my truck up in the hills Saturday, ol' 2wd did great in the snow, much better than I exptected. Made it up a steep snowy hill #ad


Vaughn

------------------
"Blue Thunder" & NW BOMBers
'01 2500 QC Shortbed 2wd, Patriot Blue over Driftwood, HO 24v Cummins & 6-speed, 3. 54LSD, Cab & Fog lamps, Camper & Tow Pkg.
BOMBings: RV injectors, PS Boost module, Amsoil air filter, straightpiped exh. , SS fuel lines, debadged body, AutoMeter Sport Comp gauges, Amber turn signals, 55w halogen rev. lights.
 
Before commencing on a Prime-Loc witch hunt, why don't you list the actual numbers you have seen rather than just say "... the Prime-Loc takes away a huge percentage of fuel pressure... " Just because you may have seen one truck with lift-pump fuel pressure problems, and coincidentally a Prime-Loc installed, is not near enough evidence to absolutely conclude the Prime-Loc system is a POS. Sorry, I don't buy it.

The real issue here is overall lift pump health, which has been more than adequately covered in past threads. Whether or not one has a Prime-Loc, low lift pump pressure and flow can roast the VP44.

I have a Prime-Loc on my '99, and I see at least 9 psig at idle, and approx. 13 psig after cranking the engine over with the pump in the higher output mode.

------------------
 
I had the same problem about a month ago. Tested my pressure at the fuel filter test ports not OK 8 lbs. Took it to the Dodge dealer twice -DC said take it off its causing a 5-6 lbs. restiction and there was nothing they could do until I took it off. When I did I got the same pressures at the test ports. My test. So then DC changed out the lift pump and reflashed the ECM and PCM under warranty. The dang Prime -Loc is setting in the garage, I can,t bring myself to put it back on without being able to check pressure at the pump which I don,t know how to do? Anybody want a $300. 00 Prime-Loc cheap E-mail me.
 
I had the same problem about a month ago. Tested my pressure at the fuel filter test ports not OK 8 lbs. Took it to the Dodge dealer twice -DC said take it off its causing a 5-6 lbs. restiction and there was nothing they could do until I took it off. When I did I got the same pressures at the test ports. My test. So then DC changed out the lift pump and reflashed the ECM and PCM under warranty. The dang Prime -Loc is setting in the garage, I can,t bring myself to put it back on without being able to check pressure at the pump which I don,t know how to do? Anybody want a $300. 00 Prime-Loc cheap E-mail me.
 
Drag racer, is the reason you are a bit angry because you have a Prime-Loc? Anyways, read on...

The pressure drop was not present on one truck... It was present on two, and both were equipped with the Prime-Loc. So here's some numbers for you to chew on...

With the Prime-Loc installed, pressure at the inlet side of the stock filter head was 13. 6 lbs. Pressure after going through the Prime-Loc was less than 1 lb, under light acceleration.

We then changed the fuel lines going to and from the Prime-Loc with 3/8" hose, and gained a whopping 2 pounds of pressure, bringing us up to 3 lbs under light acceleration. Still way below an acceptable level.

We then removed the Prime-Loc, and tested fuel pressure again. Pressure at idle at the inlet side of the stock filter head was 13. 6, and on the outlet side it was 13. 5. Virtually no drop at all. Under light acceleration, fuel pressure was in the normal range.

So for that percentage figure... it was a 78% drop at its best, with the larger 3/8" lines installed.

John, please post your fuel pressure figures, as I wasn't there on Saturday to see it. Thanks! #ad


Now about that witch hunt...

HEHEH
 
Evan. . nice post and followup! I say you have done a great job of posting the numbers, and if dragracer wants to "buy" it or not, who cares??? Let him do his own test, or just leave it on. When something goes wrong, he can blame it on cummins or dodge.

We all know there is a lift pump problem. It goes from the HVAC level down to stock. We also know there was an injection pump problem. Unless you are blind, or a Primeloc employee, you should immediately test your system.

THERE WILL BE NO WITCH HUNTS ON NW BOMBers!

PS: Evan, can I borrow your broom tonight?
 
Sorry drag racer I'M NOT BUYING IT! Kat, where's that BS flag... I need to raise it!

Many trucks have been checked now and the evidence is very conclusive (on the trucks tested).

PLEASE READ THE OTHER PRIME-LOC THREAD IN THE PRODUCTS FORUM. Some very specific testing data (albiet, not all) has been listed by me in several posts... you can either choose to believe it or not... I really don't care! Evan and I just wanted to convey a warning to our fellow TDR members. . not get flamed! #ad
Keep in mind I'm not getting anything out of this except for possible longevity of my Ram. Also, I don't feel the need to prove a d*mned thing to you drag racer.

Numbers? OK, a high of 9 psi at idle (at the OE filter head inlet port. . BEFORE Prime-Loc)... a low of -2. 2 psi (THAT'S MINUS!!!!) at light to light/moderate throttle (at the OE filter head outlet port. . AFTER Prime-Loc), with other data collected at the inlet/outlet ports on the Prime-Loc filter mount which vehemently dispell the dirty/clogged filter theory.

PLEASE READ THE OTHER THREAD... . in the Products Forum.

[This message has been edited by John (edited 11-15-2000). ]
 
Turbo Terry, check this at the fuel filter outlet port (brass plug on top of the fuel filter head on '98. 5 and '99 24v Rams). This will be pretty close... especially if you have the Aeroquip -06 AN hoses/fittings.
 
TT if your truck is a '98. 5-'99 there's no provision for checking the fuel pressure right at the injection pump. The outlet side of the filter head should be the same pressure. If you really want to check it at the injection pump you can buy the banjo bolt from a '00 or '01 for the fitting at the injection pump and the schraeder valve that screws into it. On the '00 and '01 they don't have the test ports in the filter head, two of the banjo bolts are drilled and tapped in the top of the bolt and a schraeder valve is in there to test pressures.

-Steve
 
I removed the injection pump inlet banjo bolt,drilled and tapped it to 1/8"NPT,that's where my fuel pressure sender is installed. It's very easy to do if you drill from the inside of the bolt towards the head,it keeps the drill centered. Just make sure you debur and clean it well before reinstalling.
 
The pressure at the inlet to the injector pump will NOT be the same as the pressure at the outlet of the filter. Remember that pressure loss through the line is what causes the pressure to be lower at the filter than the lift pump discharge. The same is true from the filter to the injection pump (probably about the same amount of pressure loss here as there is from the lift pump to the filter). All of this sums up the reason that everyone upgrades the fuel lines.
 
Just a note small fitting, high pressure more speed of fluid less fluid delivered to eng . Pumps don't make pressure restriction do. stock 99 3500 isb
Originally posted by Evan A. Beck:
#ad
Hey guys... #ad


I know you may not like to hear this, but the Prime-Loc system on 24V ISB trucks could cause injection pump failure.

Here's why:

The fuel lines Prime-Loc supplies with the kit are far too small. Take a look at the fittings on the ends, and you will see that they are VERY small, about a 1/8" passage for fuel to go through. The small lines and added hose are just asking too much for the little lift pump. It has to suck fuel from the tank, then push it through the Prime-Loc maze of hoses, and then through some banjo bolts, and finally to the injection pump.

After doing pressure tests on a couple of trucks, we found the Prime-Loc system takes away a HUGE precentage of fuel pressure, and delivers (at most) only a couple pounds of pressure to the injection pump. Not good at all, especially because the VP44 is lubed and cooled by diesel fuel. ABout 70-75% of the fuel supplied to the VP44 is returned to the tank, and if it doesn't get enough fuel (both in pressure and volume), the pump will overheat and fail. One truck in our shop, a '99 to be exact, did have an injection pump destoyed due to low fuel pressure caused by restriction of fuel in the Prime-Loc.

So my advice to you guys with the Prime-Loc is to test your fuel pressure ASAP. Especially you guys with modified engines.

ACCEPTABLE FUEL PRESSURE:

While cranking, the pressure should be between 5-7 psi, according to Dodge specs. With the engine running, fuel pressure should be a minimum of 10 psi, according to Dodge specs. If the pressures test below this with the Prime-Loc on there, remove the Prime-Loc, and test it again. If it still tests low, you may need a new lift pump. If your pressures are higher than the figures mentioned above, great. #ad


If the fuel pressure is low with the Prime-Loc installed,a nd is OK with the stock filter setup, I would suggest calling Prime-Loc and informing them you are having a fuel pressure problem.

Also, get your overflow valve checked as well. It should be opening at 14-16 psi. Overflow valves can malfunction by either sticking open, or opening too soon. So be sure and check your overflow valve!

Bottom line...

Get your fuel pressure tested! It may save you an injection pump!!!

Be sure to post your fuel pressure test results here, I am VERY interesting in seeing what your pressures are.

BOMBED #ad
Click to expand...
 
Id like to dig up this old thread so maybe someone like me will catch a clue and throw there prime locs away. I have major restriction with mine. I can get 11 psi after the filter but with no volume. i bump the throttle and the pressure drops like a rock to negative numbers. vacuum=cavitation=dead vp44. Just lost my lift pump and i went on a hunt. I am mechanically disinclined and was taking my fuel pressure measurements from the wrong side and it is fantastic before the primeloc (15# idle and no lower than 9# wot ),and drops like a rock after. I hope that after i remove this obstruction to fuel flow that my 9# wot is still there. No one informed me of the possible restriction so i never looked. ive been running this setup for 120k. I can say that ive been blessed with a sturdy vp44 but why temp fate. especially at that price.
 
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Issue 128 – Digital Version
Digital Magazines
FREE!
TDR Test Drive - Digital Edition
Renew
Subscribe
Gift Subscriptions
Back Issues
Subscription Status
Address Change Form
Buyer's Guides
Ram Diagnostic Trouble Codes
The Perfect Collection
The Perfect Collection Vol. II
TSB Updates
Dodge/Cummins Historical Overview
Cameron Collection
What Makes Us Tick?
Product Showcase
Advertising



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