I see...Do stupid...truck goes boom!
Now back to the original lower pulley question.
OP Most folks do the Pulley, Plugs and Tune (PP&T)
For me, I went with a 6lb lower, NGK-TR6 plugs (colder) and a tune.
That is a good wake up...then later I did the street version valve body.
For the money the valve body makes a big difference in performance.
It makes a great Daily Driver (DD) street setup. Happy foot! Lots of smiles.
(I can chip third)
Thats awesome, chirping in any gear is good. I think the pulley will work out. I will check the relays tomorrow TJ. I am leaning towards the chip program of faulty pumps. After the chip was programmed my theft light continues to flash, something about pats. Not aure but gonna check it out as well as fuel pressure test to see whats going on.
Ok sounds easy enough, only problem is knowing first of all what is a leg, the pic you sent me is clear when talking about hi/low relY and fuel pump relay i think. Would you be able to tell or show me how to test relays of legs? In the pic you show the ic relay, what does this have to do with the fuel system?Originally Posted by throttle jockey
I'm pressed for time right now so I can't type out a thorough reply, I'll try to do that later tonight...
Ls/HDs have a fuel pump relay and a fuel pump high/low relay. The pumps in these trucks do not run at constant full voltage, under normal drive conditions the high/low relay is open so voltage is reduced by the drop voltage resister which feeds only partial voltage to the pumps. My point... make sure your tapped into the right leg of the right relay. Use a test light to check the relays and ensure your wired properly.
The relays listed are the ones I most commonly have to point out for various troubleshooting procedures. In your case disregard the IC pump relay and Inertia Switch relay.
I'm not much of an electrician and the proper terminology escaped me at the time I was typing that post. I believe "lead" or "pin" are proper names for the "legs" I referred to in my previous post. They are the male spades on the underside of the relay that plug into the fuse block.
"Jumpering" (bypassing) relays is sometimes necessary when members are troubleshooting fuel pressure and fuel delivery issues. Jumpering the relay consist of removing the appropriate relay and placing a piece of wire between two contacts so an intended function happens. For example, jumpering the high/low relay as shown in the pic below runs the fuel pumps at constant full voltage.
I am not certain of the similarities and differences between the NA F-150 fuel system and the system used in Ls/HDs. Obviously there's the addition of a second fuel pump to meet the added fuel demand. The L/HD system is a return system, I'm not sure if the NA F-150 used a return or non-return system. As I mentioned in my earlier post, the factory L/HD fuel pumps do not run at constant full voltage. Under normal driving conditions some voltage is "bleed off" and released in the form of heat by the drop voltage resister (pictured below). I am willing to bet you do not have a drop voltage resister wired into your fuel system which may explain your current issues. On a L/HD the drop voltage resister is mounted under the front of the truck near the heat exchanger.
When certain conditions (load, MAF, etc.) are met the ECU commands full voltage to the fuel pumps. When this happens the fuel pump high/low relay as I understand bypasses the drop voltage resister so full voltage is sent to the pumps which in turn increases fuel pressure.
Base fuel pressure (FP) per Ford is 39.5 PSI. For sake of ease we usually say 40 PSI is base FP. FP is controlled by the fuel pressure regulator (FPR) which must have both vacuum AND boost references to ensure proper fueling at all times.
-For every 2 In./Hg. of vacuum applied to the FPR the FP will decrease by 1 PSI from the base FP.
Example - If your truck idles at 20 In./Hg. you will subtract 10 PSI off the base FP of 40 (40 PSI - 10 PSI = 30 PSI at idle).
-For every 1 PSI of boost applied to the FPR the FP should rise 1 PSI above the base FP.
Example - If your truck makes 12 PSI boost at WOT you will add 12 PSI to the base 40 PSI (40 + 12 = 52 PSI at WOT)
For ****s and giggles:
1) jumper the fuel pump relay and turn the key to the "on" position, note the FP (should be the base FP of 40 PSI). This will also keep the pumps running instead of priming the pumps then shutting off.
2) jumper the fuel pump high/low relay and turn the key to the "on" position, note the FP. I'm a little rusty, the truck might need to be running for this one. As I mentioned previously, jumpering the high/low relay circumvents the drop voltage resister. If you don't have a drop voltage resister this may be part of your headache and jumpering the relay might be a way to pinpoint that as an issue.
3) if you're really bored jumper both relays simultaneously, turn the key to the "on" position and note the FP.
Ok, cant wait to. Try it tomorrow morning. I will let you know. Thankyou.
Whelp, this is cool. Not sure its right but may help resolve issue. Ok first of all i do not have the resistor nor did My truck have one before. My fuel system does have a fuel return line. So this morning i ran the jumper on the high/low with fuel pressure gauge hooked up. With the key on it jumps up to 40psi then backs off and comes to a rest at 31 with just key on. When i start it does the same thing, up to 40 psi then back down at idle. When i rev it up pressure jumps up to 55 psi, then back to 31 at idle. Just for giggles i disconnected the vac line from Fpr. Pressure when up to 40 psi and stayed whether at idle or reving it up. The trucks runs and sounds good. I am showing about 22 psi vacum on vac/ boost gauge at idle. Not sure what all this means, can you shed some light on it for me please. Oh one other thing, when i trun key completey off pressure drop to about 10 psi almost immiedtly. ?????
I'm on shift so again I will try to offer a better reply later this evening. Before I tackle those findings though let me ask, what where the results of jumpering only the fuel pump relay?
Actually I didn't try just the fuel pump relay with hi/low relay in. I will tonight when I get home and let you know
I bypassed the resistor by wiring together and woola, engine starts, fuel psi at idle@ 39.5. Drove it today, runs strong but trans seems a little confused. I think the harley had the 4r100 which is what the pcu is that came from the h/d. I have a 4r70w, bulit to the hilt, additional set of clutch packs, hd torque converter, valve body extreme upgrades. The tuner set to the chip up to allow me to drive to the dyno, Tuesday at 0900. Cant wait. I guess now i try to find a fuel sys resistor. Or do i need it? Oh ya, success was with all relays installed and only the fuel resistor connection hard wired.
Last edited by NF-155; 11-01-2015 at 07:49 PM. Reason: Addiitional info
Did you determine the fuel pump relay to be bad?
Your base FP is good, does it fluctuate as I decribed in a previous post?
It should decrease 1 PSI for every 2 In./Hg. of vacuum and increase over base at a 1:1 rate during boost. If your tune isn't set to run the pumps at constant full voltage and your high/low relay isn't jumpered then you won't have full FP in open loop fueling.
You don't have to install a drop voltage resister but if you don't your tune must run the pumps at constant full voltage. If you run the pumps at constant full voltage it is highly recommended to replace the factory fuel rails with the rails from a '97 F-150 so you can use an adjustable FPR. Another option is a kit sold by Because Racecar that will allow you to run an aftermarket FPR with the factory rails.
Last edited by throttle jockey; 11-02-2015 at 02:00 AM.
Yes it does flucuate, I havent really put to much to it unitl I get it tuned tomorrow. I will let you know. As far as the tune I am going to install the resistor and not run the pumps at 12v for now. Maybe later it will be a project with the 97 fuel rails. I will post results of dyno after tomorrow.
Ok, so for those of you following my pioneering efforts on my swap here is the latest issue. Finished swap including engine harness, pcu and fuel harness along with s/c and everything that goes with the swap. The truck was with the tuner yesterday along with me for 7 hours. Heres the issue. Ibeleive the harley trans was a 4r100, my trans is a built 4r70w. Whicj i had completetly rebuilt in July. It worked great and had very strong shift points. The shop that rebuilt put an additional set of clutch lacks in, heavy duty torque converter and shift kit in. The builder told me it was going to shift hard and i wanted to change it bring it back in. I didnt as i was comfortable with the shift. The issue i didnt forsee was the old pcu is programed for the 4r70w and the harley pcu is programed for the 4r100. It gave the tuner fits trying to set the truck up. Its throwing codes left and right. When i left the tuner the shift point from first to second happens at 10-13 miles per hour and the rest also early. The problem arouse driving home on the intertsate. You have to literally puch the gas pedal 3/4 of the way down to get it to downshift. As i am driving i step on it to accerslte, it downshift into second at 65 miles an hour. I left off the gas and its now not shifting back into drive or od. I pull off the road, turn it off restart and try again. I now have no od or drive. If i start in od from a stop it shifts from first to second, but no drive or od. Leaving it in od i take off it shifts into second, at 40-45mph it stays in second and when i let off the gas it is like pushing in a clutch. You rev it up and down without any engagement from the trans and stays this way until you come to a stop and you take off only to repeat. Any ideas on what would cause this and any suggestions regarding how to program the pcu back to the original shift points?
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