Engine/Transmission (1994 - 1998) Major 3 gauge hold-up, any help please

[Diesel Fever]

I have for the most part got my ISSPRO fuel pressure, boost, and pyro gauges installed. But when I fired her up, none of them the worked. I have the boost gauge 1/8 fitting into the intake plate where the airhorn meets the engine, and the hose meets it and is tight. The hose has no kinks either and is tight into the gauge, but no readings. For power for the pyro's thermostat, we got power from the fuse block under the hood that sits on the left wheel well next to the left battery. Wired the positive and negative cables along with an inline fuse but no readings either. As far as the fuel pressure guage, I replaced the banjo bolt on the fuel/water seperator with a tapped one and ran a hose to the isolator. We filled as much anti-freeze as we could in the small hose for the gauge and bleed as much air as we could from the isolator, but no readings either. And on top of all that, the lighting is all screwed up aswell. I spliced a power wire from a harness we made up to the light (sky) blue wire in the headlight lamp harness. I tested for resistance with an ohm meter and it moved back and forth with the dimmer switch turning for that wire, but now the lights only work along with the buzzer along with the key in, or headlights on without the key in... . yeah. I re-tested the wire and found another wire that has resistance with the dimmer switch aswell, it is the thicker green wire in the middle... would that be the correct wire? I apologize for this very lenghthy thread but this has got me to the point beyond confusion and frustration. Please any help would be gold to me now, so I appreciate it, thank you.

 

[KHelfrich]

instead of checking resistance on the dimmer wire just check voltage that is what i did

 

[Pliska]

Wayde,

As mentioned above, you need to check for voltage at your dash light source.



For the boost, what conditions are you checking? Do you have enough load on the engine to generate boost?



For the pyro, is the gauge moving at all or just dead?



For the fuel pressure, please try the following:

remove the tubing and fitting from the "gauge side" of the isolator. If the isolator is mounted such that the "gauge side" is not pointing straight up, disconnect it from its mount and temporarily position it in that orientation. Use something with a dull end (I use an old wooden chopstick) to poke the diaphragm/piston of the isolator all the way down. Refill the isolator with antifreeze, then reinstall the fitting and tube. Go to the gauge side of the tube, and fill it as much as you can (using a syringe or turkey baster) then reconnect to the gauge.



Regards,

Michael Pliska

 

[KCraft]

fp gauge mine gave me problems with the isolator. Eliminate it!!! mine works flawless now that i took the isolator off.

 

[Diesel Fever]

Update:



Hey guys thanks for the inputs, it turned out I actually had a bad source for ground. Apparentally there was power being drawn from the negative terminal on the fuse block under the hood, not sure why, but that's what was screwing up the lighting and not allowing the pyro to function at all. I just took the cables off and found a better spot where they were alone and now they all work fine. Lighting is good, and the pyro now has the constant power it needs so all is well. Thanks again for all the inputs.



As far as the fp gauge I actually had to get a new ferring for the hose connection, gonna do it tomorrow and should work. Anyone know how far the hose has to go into the isolator? Does it have to touch the diaphragm? Thanks again, take care.

 

[monkeyman]

I ran my gauge lights right to the fuse, it was the easiest for me.
Rick

 

[Missouri Mule]

You need to drive the down the road to get the boost going.



I just put in gauges last week (with help) we used the lighter hot wire (as suggested) for the egt guage. For the ground we used the lighter ground for the Egt guage and lights for both egt/boost guage. For power for the gauge lights we used the wire to the a/c heater controls lights ( long connector on side: orange wire). Don't have lighted ash tray.

 

[Diesel Fever]

Hey guys just wanna say thanks for all the inputs and help. I have one more question regarding the fuel pressure gauge. I actually had to get a new ferring for the hose connection that goes to the gauge itself, gonna do it soon and should work. Anyone know how far the hose has to go into the isolator? Does it have to touch the diaphragm? Or, just be right at the edge? Thanks again, take care.

 

[hsmith]

Can't help with that one. I choose not to use the isolator.

 

[WDixon27]

anything past the compression fitting on the fuel pressure lines is not doing any thing, it would probably be bad if you poked it far enough in so that it touched the diaphragm, after about 2 years my isolator crapped and i hooked it straight, a good way to load up the isolator is to blow from the gauge side and then top up with the fluid of choice, you will need a valve of some kind to choke the pulses from the lift pump or it'll bang on the gauge eventually breaking it or at least make it make a ticking sound, i tried the isspro damper but the largest diameter insert was still too tight for the gauge to not take about 4 miles to come up to pressure in the morning, if you got a 30# gauge it will be near pegged if your OF valve and lift pump is in good shape, i found my truck likes about 30-32# going down the road and the general range the way i have my OF valve tweaked is 28-35# which is right in the middle of my 60# gauge. a tweak i did with my gauge set up was to add a rheostat between the pillar gauges and the connection to the dash lights as the pillar gauges were too bright with the dash lights all of the way up the way i like them, you can just grab one from a junk car as long as it just has 2 wires it'll be simple but you could get something from radio shack too, i zip tied it under the dash out of the way as you pretty much leave it alone after setting it the first time

 

[Pliska]

As mentioned above, you don't want any of your fuel pressure gauge tubing poking into the isolator, it should just be long enough for the ferrule area.



In place of a snubber, many people are having good results using a needle valve. ISSPRO has them (but currently out of stock) R7742, you can also find them at NAPA as P/N WH682, may need to be ordered in from their warehouse. It ends up working as an adjustable snubber - just tighten it down to the point that the gauge fluctuations stop.



Regards,

Michael Pliska

 

[PRohr]

I had to put the needle valve in on my truck the Isspro snubber was not enough. I was working with my vendor and Isspro to solve a ticking FP gauge problem. I had 4 gauges go bad... . I bought one, it starting ticking, Isspro warrentied it. I smoked the second one when I put my Fass in and hooked it up direct without the snubber. I bought another and put the snubber in and it worked for about 2 weeks and then the needle started bouncing and ticking again. After talking with my vendor, Fass and Isspro we decided to put the snubber and the needle valve inline and that fixed the ticking and needle bouncing and then Isspro snet me another gauge to warranty that one as the stepper motor was trashed but we didn't want to blow up another one. I can't say enough good about Isspro and they staff... ..... they really stepped up to the plate and I think all of us wanted to figure out what was going on with this gauge. Most of the issue was caused because of the pulses in the 12v system but I think if you have a mechanical pressure gauge the needle valve posted above is a MUST!