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I have the Stancor 902 GPR relay in my truck. Just recently I noticed that my truck has an extended cranking time when cold. Then at times it would start right up after I wait for the WTS to go out.

I've been paying attention to volt meter on the cold extended crank times and noticed the meter is in the middle, no dim lights, nothing that would tell me that the GPs are activated. So this lead me to believe that the GPR is not activating/closing.

When motor starts right up, the GPR is cycling on/off for the specified time command by the PCM. Is this cycling normal or are the GPs supposed to be energized continuously?

Now....I'll throw a twist into this situation. I have the 215A Mitsu alternator which is more than capable to keep up with the GPs. Now when the GPR cycles, it's getting 14.5v every on/off cycle. According to Stancor, careful attention needs to be paid attention to systems with a 12v charging system. My alternator puts out 14.4v-14.5v, I'm obtaining this reading through the AIC/PCM. It could be higher at the GPR because it's connected directly to the batteries.

Also, how many have their Stancor relays mounted horizontally? Stancor recommends the terminals be mounted up.

So which relay is needed the 586-902 (12v coil) or the 586-903 (15v coil)?

Here is some reading:

http://www.stancor.com/pdfs/Catalog_2006/Pg_056_57.pdf

http://www.stancor.com/pdfs/Catalog_2006/Pg_094.pdf (note step 6)

Billy T.
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What went out? The coil or the contacts? As far as which one I think that the 12 volt one is the right one since once the contacts are pulled in then your voltage drops to below 12 volts.
 

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Discussion Starter #3
What went out? The coil or the contacts? As far as which one I think that the 12 volt one is the right one since once the contacts are pulled in then your voltage drops to below 12 volts.
I'll have to test it out. Maybe contacts burnt up or have a high resistance where no power is getting through.

Billy T.
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The circuit is not supposed to cycle. That sounds more like a problem with one of the GPs, drawing too much current and causing the relay to open. I'd start by ohming out each glow plug.
 

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The circuit is not supposed to cycle. That sounds more like a problem with one of the GPs, drawing too much current and causing the relay to open. I'd start by ohming out each glow plug.
If I'm going to have to do that, then I'll convert to a SD set up.

Billy T.
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The circuit is not supposed to cycle. That sounds more like a problem with one of the GPs, drawing too much current and causing the relay to open. I'd start by ohming out each glow plug.
No, the system IS supposed to cycle to protect the gp circuit.
Almost all '97's do this with. PCM won't allow more than 14.1v (I think, maybe 14.2) to the gp's, if volts go up it cuts of the cuircut till it drops, then kicks them back on etc. On-off-on-off, sounds like the idle hunts. It's totally normal, though I don't like it. When my truck starts to do this I turn the headlights and HVAC fan on to create enough draw to stop it till the gp's shut off.



How old is the Stancor?
I've been curious if it would hold up to motor vibrations. I would have mounted mine on the pass. fender just to be safe, but I never got one. I just stick with stock replacements.
 

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Billy I've had the exact same problem with my truck and it's driving me nuts! My truck is a late 97 and the gp's never cycled before. I too am running a larger alternator, not a 215 but a 190 which makes 130 amps at idle. I put that in beginning of last June and had zero problems until December. Thought it was my Stancor so got another but that did nothing. Tried my good stock relay same problem. Checked the wiring and gp's - tested everything but could not find any problems. I converted my uvch to the SD style and at the same time put in a brand new spare set of gp's - still no luck. Tried a NAW4 pcm from a 95 truck to see if it was my pcm but again the gp's still cycle on/off. It's annoying as all hell esp as it had never done this at all.

Does yours do this all the time? Mine will on a cold start say 50° or colder. Above that the plugs stay on continuously for up to a minute or so, sometime only ~30sec and behave normally.

If the pcm is protecting from too much voltage can a resistor be installed so the gp's never see more than something like 13 volts?
 

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Discussion Starter #8
No, the system IS supposed to cycle to protect the gp circuit.
Almost all '97's do this with. PCM won't allow more than 14.1v (I think, maybe 14.2) to the gp's, if volts go up it cuts of the cuircut till it drops, then kicks them back on etc. On-off-on-off, sounds like the idle hunts. It's totally normal, though I don't like it. When my truck starts to do this I turn the headlights and HVAC fan on to create enough draw to stop it till the gp's shut off.
Mine does exactly as you posted

How old is the Stancor?
1.5 years old

I've been curious if it would hold up to motor vibrations. I would have mounted mine on the pass. fender just to be safe, but I never got one. I just stick with stock replacements.
There has to be a better one out there. I'm temped to try the Western Plow one for less than $15

Billy T.
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Billy I've had the exact same problem with my truck and it's driving me nuts! My truck is a late 97 and the gp's never cycled before. I too am running a larger alternator, not a 215 but a 190 which makes 130 amps at idle. I put that in beginning of last June and had zero problems until December. Thought it was my Stancor so got another but that did nothing. Tried my good stock relay same problem. Checked the wiring and gp's - tested everything but could not find any problems. I converted my uvch to the SD style and at the same time put in a brand new spare set of gp's - still no luck. Tried a NAW4 pcm from a 95 truck to see if it was my pcm but again the gp's still cycle on/off. It's annoying as all hell esp as it had never done this at all.

Does yours do this all the time? Mine will on a cold start say 50° or colder. Above that the plugs stay on continuously for up to a minute or so, sometime only ~30sec and behave normally.

If the pcm is protecting from too much voltage can a resistor be installed so the gp's never see more than something like 13 volts?
I'm trying to remember back when I installed, 1.5 years ago. I did not have any issues starting until the temps started to get warmer.

During the cold winter months, the motor would fire right up in the single digits without a hiccup. Once the temps began to get in the 50* range, i got extended crank times.

With the lower temps, the GPs would cycle on/off, had that surge at idle. Now my chip(Beans/Jonathan tuning) has the SD start up files on it. I would get an elevated idle (1000 rpm) automatically when it was cold. The elevated idle rpm would depend on the temp outside.

Now that the temps are warmer, I developed an extended crank. I waited a few seconds after the WTS turned off before cranking. It made no differrence.

Last night, I put a test light on the load side of the relay. After the motor started, it was steady for about a minute and it turned off. Now I don't know the condition of the internal contacts or if the GPs are getting full power.

This is where I'm at now. This has me confused because it's harder to start in warmer temps. After the motor warms up to running temp, it starts right up.

Billy T.
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There has to be a better one out there. I'm temped to try the Western Plow one for less than $15
Plow solenoids are only rated for a few second bursts at a time. I doubt they would hold up to a 2 mintue draw every day.

There are plenty of continuous duty solenoids available, however, from places like McMaster-Carr.

Personally I think I have only replaced 3 GPR solenoids in the 11 years and 6 different trucks I have owned. I just don't have an issue with the stock replacement parts. ???
 

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Sounds almost the same as mine except my truck will fire right up no matter if it's 5° or 50° - no extended crank or hard starting just the annoying gp cycling.

Fwiw my Stancor is just over 3yrs old. I replaced it thinking it was the problem but the new one acted the same so put the old one back.
 
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