so, this is weird

[cbarr300]

maybe ya'll can help me....been a big help in the past.

Well, I've been having some problems with my car here recently. I just can't figure this thing out.

Here's the rundown:

I'll try to crank my car..but when I turn the key to the acc level (where the pump is supposed to prime) the pump USUALLY doesn't prime. Keep in mind I have a paxton inline pump and no in-tank pump. Well..I jumped it to see if the pump was shot or not and it started turning over after applying the hot wire (This showed me the pump had a good). Well I reconnected the fuel pump connector to the wiring and turned the key and the pump primed..but it did sound like it was dying out after it started (I attributed this to the fuel lines gaining pressure). Also, after it is primed my fuel pressure gauge is showing like 15 PSI of pressure...Is this normal for cranking pressure?

After doing this it'll USUALLY crank. Then if I cut it off and back on it'll crank again....again, USUALLY being the key word. Sometimes I have to go and re-jump it; then it'll start working.


Any ideas what-so-ever...I'm pretty much lost. Could it possibly be the CCRM?

I'm not sure if this is related...but my fan also comes on after the engine is cranked and will stay on until it is off. There is no manual control type switch so this is kind of on the weird side. I know the CCRM controls the fan as well..so I'm thinking it might be my CCRM going bad. Do they normally start going bad...or do they just completely crap out?

Thank you for your time
Clay

 

[HISSIN50]

Clay, that was a lot to decipher.

Seeing 15 PSI is not normal after a prime-out - it's low. BUT: we don't know that you're getting full voltage to the pump (more voltage = volume-movement, which equates to pressure).

You can test the pins at the CCRM for the fuel pump. The relays normally fail so the pump doesnt work (which is their resting position).

For the fan, make sure Pin 14 on the CCRM doesnt show 12 volts, and that Pin 17 doesnt show ground.
Make sure the ECT is plugged in. An open in the ECT will trigger the fan to be on. A bad driver in the puter can make the low speed come on (via the EDF relay control).

Good luck.

 

[cbarr300]

Yes, sorry about the length and the numerous amount of questions there hissin. I've just been hunting down quite a bit of problems and am reallllly anxious to get this car running right. I haven't been able to have fun with it since I inherited it 2 months ago. Heck, I'm still trying to learn what all was done on it. I'm trying to get this thing running before I have to head off to college.

So as far as the voltage is concerned at start-up...it should be seeing a full 12 volts in the acc position, correct? The battery was moved to the trunk so there is a possibility there could be something screwy with the wiring.

 

[HISSIN50]

So as far as the voltage is concerned at start-up...it should be seeing a full 12 volts in the acc position, correct? The battery was moved to the trunk so there is a possibility there could be something screwy with the wiring.

It's tough getting a car that you don't know the modification pedigree of.

Yep - technically you should see 12.6 volts with the key turned to accessory. And while cranking, it can dip as low as about 10 volts with a semi-dead battery (when it gets into the 9's, it's hit or miss as to whether it will start).

Sometimes the grounding for the trunk-mounted batteries kinda sucks. See Justin's Cardomain page for how it should look. Now I dont think that's your issue though - just something to do sometime when you're bored.

For the FP relay in the CCRM:
Pin 5 should be power to the pump.
Pin 11 should be battery power to the common FP relay terminal.

And I *think* (I'd need to double-check) that Pin 18 is ground from the computer to energize the relay.

It sounds like you're not seeing Pin 5 having 12 volts when it wont prime. If that happens and Pin 18 doesnt have ground either, then the control side of the relay would need addressing.

One quick thing to check: Pull the fuel pump fuse and inspect it and it's terminals. A bad connection could be causing you some issues.



Good luck.

 

[cbarr300]

ok, quick update...I got called into work so I didn't have much time to mess with the ccrm but I did check the power going to the fuel pump. I got 11.64 volts going to the fuel pump...with my battery at 11.71 (kind of on the low side due to constant cranking but the same thing happens with a freshly charged battery)

The thing that throws me for a loop is this: how would the wire going to the fuel pump be reading 11.67 volts...but yet the fuel pump doesn't kick on? However, the fuel pump WILL work when I jump it with leads from the battery which is not even half a volt higher. THEN, after jumping it and reconnecting the fp it will start priming without help from me (but it eventually goes back to me having to jump it).

This just makes no sense at all, lol.

Am I missing something that the CCRM does? Sorry for all the questions.

 

[cbarr300]

ttt

 

[HISSIN50]

Someone refresh my memory: On SN95's is the inertia switch on the feed side of the power to the pump? I thought it was (on foxes, it is on the control side). So you could have power being stopped at the inertia switch. You could try the same test but first pull the inertia switch out and jump the terminals (bypassing the switch for a minute for testing).

This would be the impediment between the CCRM 'output' to the pump and the pump itself.

You could also simply pull down the electrical connector for the pump and put your meter on the leads and see if it shows 12 volts. If you have 12 volts at the output of the CCRM but not at the pump, check the inertia switch for 12 volts-in, but not out.

Otherwise, it could be a semi-broken wire in between the CCRM and pump.

Good luck.

 

[cbarr300]

Thanks hissin, ur information has been a huge help. The connector to the fuel pump...like a foot away from the actual pump...shows good voltage. The only thing I could think of is that maybe one of the wires got burnt and it is showing voltage...but not getting the correct amperage going through it.

other than that I'm at a loss. I have a day off tomorrow so testing will be done then.....i was gonna do it tonight but it decided to pour after I stepped outside....go fig

Clay

 

[HISSIN50]

Clay, are you also running a jumper ground wire to the pump? If so, check that stock ground wire at the pump! On foxes (just a few years older) they're known for rotting. That would also cause the issue and things you're seeing.

Otherwise, you are spot on about voltage vs current. Normally if you did have a weak wire going to the pump, I'd expect the pump to fry the wire all the way after some running (the current load through fewer strands would heat the remaining strands up till they disintegrated).

Good luck.

 

[cbarr300]

hissin, I'm just running the positive wire to it. That was one of the first things I did to ensure that I was getting a good ground to it. You would think that the wire would be fried but its not...it is definately on the warm side, however.

So, I've ruled out the pump being bad since it is powering up once I use a (+) jumper wire to it. And since I used the (+) only..that shows that I am getting a good ground.

The lead going to the pump is showing the correct amount of voltage. So the pump is getting the correct amount of voltage.

So I've narrowed it down to these two things: either the wire can't flow the current like it should or there is a problem with my FP lead. Maybe the two metal pins aren't getting a good connection. I don't think this is possible since it feels pretty snug....but I'd imagine it can't hurt to check it.

Thanks again hissin, i'll update

 

[cbarr300]

Well, the pump is definately good. The fuel pressure after hardwiring it was around 39.

Now I just have to mess around with the tweecer to lean out my maf curve. Not so good when you smoke out an apartment complex with black smoke.

I left my DMM at my friends house so I couldn't check wiring or anything. But I didn't see any burn marks on the wire. I didn't check the entire wire though due to rain.

will update

 

[cbarr300]

yet another update:

I'm thinking its the relay in my CCRM. I tried it without hardwiring it (the normal way) and it worked pretty well on a cold engine. It idled pretty well and I was pretty much happy.

Then it started surging. As it was surging I looked at my fuel pressure gauge and noticed it was jumping up and down between 15 and 40. Then shortly after it would die and the pump wouldn't prime or anything.

What I'm thinking is it is getting hot and maybe the relay is failing? I'm sure this is possible, isn't it?


Oh yeah, I pulled codes and after doing it the fuel pump started working. Then it did its surge thing again and went out, again. I couldn't get it to cut back on.


on the bright side, it's progress

 

[HISSIN50]

Sounds like you're tracking it down. Since you can make it burp while it idles, I'd consider reinstalling your jumper wires at the tank's connector (if you can do that while having the oem connector connected). Put a DMM on the two wires so you can see the voltage to the pump in real time. When it hiccups, note the voltage.

If the volts dip, check real quick at the CCRM and if the CCRM voltage is good but at the pump it's not, check the inertia switch. They have been known to become resistive.

I've recommended using a stand-alone realy for a failing relay in the CCRM that doesnt matter (like the WOT relay). But for a FP, you want a really quality piece - if it fails while you're making a left turn with oncoming traffic, that'd SUCK!

Good luck.

 

[cbarr300]

Hmm, good advice. Do you think I could check this by just bypassing the inertia switch with some jumper wire?

I have a paxton inline pump and no in-tank so I have pretty easy access to the wiring. I will do the test you mentioned tomorrow and see what happens.

I'd rather not have to buy a new CCRM if I don't have to so I was thinking about setting up a relay and see if that fixes it (only extremely temp....as that scenario you mentioned doesn't sound too fun). What would be a quality relay? I heard the bosches were pretty good but have heard that they too fail occasionally.

 

[HISSIN50]

Hmmm, interesting about the aftermarket pump - if you mentioned it earlier, I forgot about it. Not that it matters though.

You could jump the inertia switch for testing - I think it's important to keep it functional in the long-run though. You really want to have the pump lose power in the event of a collision.

I double checked schematics earlier while I was workin on another car and it does appear as though the inertia switch is indeed on the load side of the pump wiring (which is a switch from how foxes were wired). So you'd want a large gauge jumper wire (on a fox, with the switch on the control side of the relay, we use a paperclip. That wont fly with the SN95 wiring).

I use a LOT of Bosch 30 amp SPDT relays and have had them fail on me. I'd look for something better quality that's made for a zillion switching cycles. The Ford stuff is good (like a relay and relay socket for a Fox fuel pump - from Ford. The parts store replacements can leave something to be desired) but it's also pretty pricey.

I'd get with TMoss, Jrichker, Monte Smith or one of the other electrical whizzes (them folks are EE's with lots of hands-on experience) who have used a ton of relays and really know. I'd honestly be taking my best guess, which is certainly something I don't want to do with your safety in mind. I know Bosch's larger capacity relays are made for tons of trouble-free cycles. But which one to get, I know not.

Good luck.

 

[cbarr300]

Wow, you have been a lot of help. Hats off to you and thanks for putting up with the questions.

I'm going to do some more testing once it clears up outside. I will check with the mentioned people and get some advice on good quality relays.

Yeah, the aftermarket pump makes the whole checking wires thing a whole lot easier. Plus it looks pretty neat as I have a sump at the bottom of the tank with a rather noticable stainless steel braided line looping around it to the pump which is on the backside of the tank.

Again, thank you for all the help
Clay

 

[cbarr300]

Also one more quick question. How would I go about wiring a stand alone relay to power the pump? I know a tad bit about electricity and circuits and what not...but just very basic stuff.

 

[HISSIN50]

Also one more quick question. How would I go about wiring a stand alone relay to power the pump? I know a tad bit about electricity and circuits and what not...but just very basic stuff.

An SPST/SPDT relay has a control and feed side. Generically speaking:

On the control side, it looks like CCRM pin 18 is the ground control pulse from the computer (this can be tested with your DMM [not a test light!] very quickly). That'd go to terminal 85.

86 would get key-on 12 volts.



Feed Side:

30: fused battery power.

87: Pin 5 on the CCRM (If I remember correctly). This goes to the pump.

You can use all the OEM inputs from the CCRM and just run them into your new relay (for a cleaner install, and to retain the OEM fuse protection, etc). That's how I'd do it, were I forced to do something like this.

We can double check the pins if you want to use all the OEM inputs (rather than sourcing any new power sources, like the battery). Your call but I'd use the OEM inputs. I'll post up a CCRM pin-out so you can see what I am if you want.

 

[cbarr300]

that'd be excellent. This would just be a temporary thing...really temporary. I just need to save a bit up to get a new CCRM...IF that's my problem. Like I said, still need to get out there and do some testing once I get my DMM back today.

Thank you,
Clay

 

[HISSIN50]

Courtesy of Texsn95 is the CCRM pin-out .

Double check me (I'm beyond needing sleep), but it looks like it'd be:

On your new relay: terminal 85: CCRM pin 18 (check this one with your meter).

On your new relay 86: CCRM pin 13

On your new relay 30: CCRM pin 11

On your new relay 87: CCRM Pin 5