12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Mechanical fuel pressure gauge

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Old 10-18-2014 | 04:30 PM
wpg6.5's Avatar
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Default Mechanical fuel pressure gauge

I actually have two questions, the first is what mechanical permanent fuel pressure gauge is everyone running? I'm having trouble finding one with an isolator. And 2 my air dog blew a fuse today and I drive my truck with no lift pump for about 15 min or so what damage if any did I do to my injection pump. Nothing seems wrong just wanna make sure I didn't toast it or do something terrible. It was being driven nice and easy as I noticed the rough idle and such.
 
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Old 10-18-2014 | 06:45 PM
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It's a 12V, your LP probably ok. They don't suffer the same level of starvation issues that the newer VP44s do. As for the mechanical fuel pressure gauge, you're probably having a hard time finding one because pretty much nobody uses them anymore. There was a time when mechanical gauges were generally considered to be more accurate/dependable than electric, but those days were long gone a decade ago. Now the only "advantage" of mechanical is that they continue to read after the engine is off and the key is back in your pocket. Not sure when this would matter, but it's true. Everyone I know is running electric gauges. That all being said, the mechanical LP does pose some... challenges... for an electric FP gauge that the mechanical gauges weren't as susceptible to, but they're pretty easy to get around. I know it isn't the answer to the question you asked, but my answer is just get a good electric one. ISSPRO, VDO, Stack, Stewart Warner.
 
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Old 10-18-2014 | 07:12 PM
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I have an airdog so does that mean I shouldn't have an issue running an electric gauge? What I wanted to do was use the Tork tek fuel snubber. If that would work id be on board in a heart beat. I just don't want to have the fuse pop again or the pump fail and not no because it's pretty hard to hear it over the engine.
 
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Old 10-18-2014 | 07:54 PM
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The Airdog means the electric gauge will be fine, you probably won't even need the snubber with it. I should have mentioned that, sorry. I'm more concerned about why the fuse popped in the first place.
 
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Old 10-18-2014 | 09:33 PM
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Ya me too. Popped a 40 in quick for the ride home then when I got home popped a 20 back in and it's been ok. Fortunately the truck came with the air dog so if I need to replace it I will. Either fass or go to one of those
Mechanical styles. Unless I could get a motor cheap for the air dog.
 
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Old 10-19-2014 | 08:01 AM
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What are the chances it didn't have a big enough fuse in it? I don't know what the Airdog requires, but for some reason a 20 sounds small to me. Someone at Airdog would know. It may be that simple... wouldn't that be nice?
 
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Old 10-19-2014 | 10:47 AM
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I got a brand new 165 sitting in my garage for my buddy, I'll just check what the fuse is in that. The relay is a 30a I believe. So maybe the fuse should be like a 25
 
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Old 10-22-2014 | 04:01 AM
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Ltk
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The fuse is a 20 amp

I had one blow, then changed and worked for 6 months then started blowing every time the truck was turned on. Fuel pressure would drop to 0 and stay there.

I replaced the pump motor and all was well. Just call with your serial number, they wont ask questions and will have you a brand new pump within 24 hours.

Hope that helps
 
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