Fuel pressure gauge
11-11-2004, 07:49 PM
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Fuel pressure gauge
I have installed a Stewart Warner electric
fuel pressure gauge and I have a problem.
The gauge is constantly pegged no matter
what the truck is doing. If the key is on, she is pegged. I have rechecked the wireing diagram 3 times and it matches the instructions. I thought it was a bad ground at the sender so I installed a jumper to the battery neg and no effect. What now??????
fuel pressure gauge and I have a problem.
The gauge is constantly pegged no matter
what the truck is doing. If the key is on, she is pegged. I have rechecked the wireing diagram 3 times and it matches the instructions. I thought it was a bad ground at the sender so I installed a jumper to the battery neg and no effect. What now??????
11-11-2004, 07:55 PM
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Ive said it before and Ill say it again......guys buy a mechanical guage. The electric gauges are a pain. Senders are troublesome and do not last. There are lots of guys running mechanical and rarely do they ever have a problem.
Check for air in the line or a bad sender. Although I would imagine a bad sender would show no pressure at all.
Check for air in the line or a bad sender. Although I would imagine a bad sender would show no pressure at all.
11-11-2004, 07:55 PM
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Is the sender open? Try gounding the sender lead does the gauge go to zero.
I have a SW gauge with two senders in my truck. I'll get you the typical ohm
readings for the senders tommorow.
I have a SW gauge with two senders in my truck. I'll get you the typical ohm
readings for the senders tommorow.
11-12-2004, 12:51 AM
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If your sender is in the pretapped location on your fuel filter housing we can rule out air in the line. Wait a minute what pressure does you guage read 0-........?
11-12-2004, 01:30 AM
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electric gauges register higher when resistance to ground is reduced. That is how an electric sending unit operates.....on varaible resistance to ground. Which is why when you ground a gauge sending wire which is zero resistance, the gauge pegs. remove the wire from the sender and turn on the ignition, if it still pegs, you have a short to ground in the wiring somewhere. If it stays at zero you have a shorted sending unit.
11-12-2004, 01:32 AM
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The sender reads full scale, above 16lbs.
I am leaning toward and open sender. I think johnnyram is on the right track. I will try grounding the sender wire tomarrow. The gauge reads 0-16 lbs. Air in the line is interesting. I assumed that air in the line would compress to what ever the line pressure was. I will investigate that also.
The senders are remote mounted from the
engine. Thanks for the responses.
Jason
I am leaning toward and open sender. I think johnnyram is on the right track. I will try grounding the sender wire tomarrow. The gauge reads 0-16 lbs. Air in the line is interesting. I assumed that air in the line would compress to what ever the line pressure was. I will investigate that also.
The senders are remote mounted from the
engine. Thanks for the responses.
Jason
11-12-2004, 01:44 AM
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Originally posted by rockwithjason
The senders are remote mounted from the
engine.
The senders are remote mounted from the
engine.
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11-12-2004, 10:04 AM
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When I tried an electric gauge one of the three senders I replaced before going mechanical only lasted about 30 seconds. If you have to buy any parts give up while you're ahead and go mechanical.
11-12-2004, 07:13 PM
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Wow 3 senders and one for only 30 seconds? 
My sender is located above the master cylinder and connected to the pump side of the filter housing with 1/4 fuel hose. Tomarrow I will investigate further.
My sender is located above the master cylinder and connected to the pump side of the filter housing with 1/4 fuel hose. Tomarrow I will investigate further.
11-12-2004, 08:43 PM
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I must be either good or lucky. It's been just over 1 1/2 years and 60k miles with the sending unit mounted to a 'BFD Industries'* bracket using an intake bolt on the engine. I had problems with the first week due to the wires being short, and no problems since. In fact, I am going to buy another sending unit and hose for the pre-filter side. I already have an ON-ON toggle switch, and can get another bracket.
*= Anytime I fabricate a tool, and sometimes parts, I mark it with ' Mfg. in US of A by BFD Industries'. My initials are BFD. Started years ago as a joke, but has kinda stuck with me.
*= Anytime I fabricate a tool, and sometimes parts, I mark it with ' Mfg. in US of A by BFD Industries'. My initials are BFD. Started years ago as a joke, but has kinda stuck with me.
11-13-2004, 02:36 PM
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Fuel Pressure Guage.
I am using an electrical sender and guage. It is working very well. I also have a Autometer manual on it and as near as I can tell they both read the same when running. I prefer the electric in the cab so this is the one that I chose to stay with. It is a Nordskog digital from 0 to 100 psi and reads from 0 to 100psi. P/N M8424 with the sending unit P/N S8434. I chose to go with the 0 to 100 psi to allow for start up surges as they go into the mid to upper 30lb range and if you are using a guage and sender that is not rated that high then it will bust it. Like I said, the one that I am using is working well and is fairly accurate. This brand is made by Stewart Warner as the sender has this on it. Price from Summit Racing at around $130.00 range for both.
11-16-2004, 07:38 PM
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ok, update time. I took my fluke meter and played around with my fp gauge today. I took a reading with the truck off and it read 265 ohms from the terminal to the case of the sender. I started the truck and took anouther reading and it was 69 ohms to the case so I am guessing that the sender is ok. The gauge was still pegged in the truck so i grounded out the sender wire and the gauge was still pegged. I reversed the ground and hot wires on the back of the gauge and the gauge bottomed out, in other words the gauge pegged the other way. hmmmmm.... the saga continues. Bad Gauge? Miswired? The terminals are I, G, and S. I assume that G is ground, I is ignition, and S is sender. That is the way it is hooked up. Suggestions?
