Engine/Transmission (1994 - 1998) Blew out my second fuel pressure gauge

[guldam]

I have a TorkTek snubber installed on my fuel injection pump, and then connected to that is an 18" grease gun hose, and finally a Marshall Silicone filled fuel pressure gauge. It's rated 0-60psi.



My first Marshall Gauge started leaking it's silicone fluid. I sent that back to the place I bought it, and they sent me a new one. New gauge has been installed for several months.



When I first change out a fuel filter and clean out the prefilter, I get a fairly steady reading around 20psi, with a 5psi fluctuation in either direction. After a driving a while the fluctuations increase to 10psi fluctuation.



This past weekend I smell BioDiesel, and I open the hood to investigate.



Gauge has a broken needle, and it's missing the rubber plug, and of course there's Biodiesel all over the place. The second gauge is toast.



I think the plug probably went first, then the needle and some gasket or something in the gauge. Big spike in pressure being the issue?



Oh, the truck has a newish TorkTek overflow valve with factory pressure setting.



So... no more Marshall Gauges, even though the manufacturer says they are designed for this application, and with a snubber I should be good to go.



What are folks using for a fuel pressure gauge?



I'm thinking an electronic version that I can run in the cab, as opposed to in the engine compartment.



Once again scratching my head.



GulDam

 

[GAmes]

One of these days I'll get around to installing an electronic gauge in the cab. That would be my choice.

 

[ata]

I've been using an ISSPRO 40 psi electric gauge for about 8 years. The sender is on a snubber (small needle valve) adjusted so the gauge needle does not jump all over the place and the gauge is in the cab. The truck is a 97.

 

[seafish]

You might want to ask the manufacturers if thier gauges and fittings are compatible with the Biodiesel.

IIRC, it is almost like a cleaning agent, breaking things down, versus lubricitious, like petroleum based diesel fuel.

Also, different rubber and plastic compounds are affected negatively by different agents.

NOT saying for sure, just someting to think about...

 

[JMetzger]

I am using Auto Meter Sport Comp. Have had it for four years & knock on wood have never had a problem. Do not have a snubber or anything, hooked straight on the VP. I have read on here of people having problems with the electric gauges.

 

[The patriot]

I have a couple of swedgelocks the instrumentation dept was throwing out at work. They've been there for 10+ years (+ however old they were when they were trashing them)with my home made needle valve/ snubber. I havent had any problems.



My setup has a tee in it so I have an electric gauge in the cab with a throw switch so I can check pre/post filter, in addition to the mechanicals under the hood The electric gauges arent particularly accurate.

I dont think the senders stay within spec very long.

I have a few pics of my setup in my photo album here.



FWIW I've been running a tork teck OF valve also.

 

[guldam]

It has occurred to me that the BioDiesel might be a problem. I know that it almost immediately softened the 90 degree hose at the prefilter.



I'll run it by the Marshall folks and report back.



Guldam

You might want to ask the manufacturers if thier gauges and fittings are compatible with the Biodiesel.



IIRC, it is almost like a cleaning agent, breaking things down, versus lubricitious, like petroleum based diesel fuel.



Also, different rubber and plastic compounds are affected negatively by different agents.



NOT saying for sure, just someting to think about...

 

[Bob4x4]

I am using Auto Meter Sport Comp. Have had it for four years & knock on wood have never had a problem. Do not have a snubber or anything, hooked straight on the VP. I have read on here of people having problems with the electric gauges.

24v totally different than the 12v

 

[Bob4x4]

I have a TorkTek snubber installed on my fuel injection pump, and then connected to that is an 18" grease gun hose, and finally a Marshall Silicone filled fuel pressure gauge. It's rated 0-60psi.



When I first change out a fuel filter and clean out the prefilter, I get a fairly steady reading around 20psi, with a 5psi fluctuation in either direction. After a driving a while the fluctuations increase to 10psi fluctuation.





Oh, the truck has a newish TorkTek overflow valve with factory pressure setting.



GulDam

20 psi is too low for top performance,turn it up a notch. I don't leave a pressure guage on all the time,not really needed on the 12 v. Just ck it if you have an issue

 

[guldam]

Well, I reckon I need a replacement gauge first.



How much of a notch? I thought 20psi at idle was about standard...



GulDam

20 psi is too low for top performance,turn it up a notch. I don't leave a pressure guage on all the time,not really needed on the 12 v. Just ck it if you have an issue

 

[budnate]

try about 25 at idle take it for a drive, you should notice it pulling better out of the hole.

 

[The patriot]

My pump has about 30K miles of off road on it and when I put the tork teck OFV in I didnt touch it. Idles @ about 30 PSI cold. Maybe the Cali blend is slightly more like a solvent than diesel fuel, and that COULD drop the psi a LITTLE. 1-2 psi I'd imagine. Besides I may have a little used engine oil in my tank that would "help" my press a little.
I replaced my fuel lines with " J30R9 " spec fuel line which is bio rated. It's quite pricey too.

 

[JMetzger]

BOB4X4, I guess old age is getting to me. I failed to notice that it was a 12 Valve but at 75 I guess I can make a mistake now & then. Thanks for helping me out.

 

[Bob4x4]

BOB4X4, I guess old age is getting to me. I failed to notice that it was a 12 Valve but at 75 I guess I can make a mistake now & then. Thanks for helping me out.

No worries,I have attacks of crs myself I am no spring chicken.

Just trying to save the op some confusion

 

[Bob4x4]

Well, I reckon I need a replacement gauge first.



How much of a notch? I thought 20psi at idle was about standard...



GulDam

I prefer 35 or better on a performance application

 

[guldam]

Thanks,



As soon as I get a new gauge, I'll try it at 35psi. Truck wants more fuel anyway...

I prefer 35 or better on a performance application

 

[guldam]

Reply from Marshall Gauges

Here's what Marshall says:



Sorry to hear about your problem. For the needle to break off like that indicates something extreme happened. From the photo it looks like failure due to extreme overpressure, a sudden pressure spike perhaps (it would have to be very rapid for the pointer to break off when hitting the pointer stop pin).



I would recommend trying a different brand and see if the same problem occurs. If you do in fact have extreme pressure spikes occuring no 0-60 psi mechanical gauge will withstand it. Mechanical gauges can typically withstand 130% rated pressure without loosing accuracy and 2x - 3x rated pressure for short periods without failing.



Is the mechanical lift pump capable of putting out an "extreme pressure spike"?



Funny how they are sending me off to break another company's gauge...



GulDam

 

[The patriot]

IMO the lift pump is not capable of pressure like that.

Also IMO the pulsating could have just done the gauge in.

If you've ever seen one w/o the snubber you'd probably agree.

JM. 02

 

[CCiatteo]

I run the same Tork Tek OFV, and I have my Autometer Z-series (0-100 psi full sweep electric) mounted in the cab. My plumbing goes something like this:



I replaced the banjo bolt on the outflow side of the fuel filter head, with a tapped version, then I have the snubber, then a 1/8NPT to -3AN fitting. From there a prefabbed -3 braided stainless line (normally used for brakes) over to the fenderwell plumbed into a "T". One leg is -3AN (from filter head), one leg -3AN and is capped (used for bleeding if necessary), one leg is 1/8 NPT for the autometer sending unit. So far so good. No leaks, fumes, blowouts, etc. And despite what others say about not needing a gauge for a 12v, once you learn to trust the readings, its very useful for determining when the fuel filter needs changing. My needle does have bounce to it, but you learn to "average" the bounce and you'll get a feel for a good reading and a weak reading (aka change the fuel filter soon) and then a really poor reading (aka change it now).



I think the haynes manual specifies 24,000 for the fuel filter, but I think that's a bunch of hooeeey. I am seeing fuel pressure starting to drop around 12,000 miles. I buy only at high volume stations, so I don't believe it to because of "old fuel", but who knows. I don't run anything but straight on-road diesel and never run additives, so take it for what its worth.



As a side note, I think Tork Tek now overs a banjo/fuel snubber combo fitting, which would be sweet. One less chance for a leak and a more compact installation.



This reminds me, I need to change out my fuel filter for the coming winter months.

 

[guldam]

Marshall Gauge Update:

I contacted Marshall Gauges, and they've replaced the blown out gauge. I will see about installing a needle valve to add additional protection against all that surging, and probably just use the gauge for testing, and then remove it. I don't think these type of gauges will survive long term connection to the 12valve Cummins.

Thanks to Marshall for replacing the gauge.

GulDam