run or not

[dec010974]

Hello to all my techies. my setup is a 1971 c10, lq4/th400 with cam, springs, and head upgrade, stock dbw harness. I'm trying to complete the wiring, see if my pcm works, and check my wiring/soldering for continuity. I needed to extend the drive side coil and injector wires (they are not connected). to check if the pcm is operational, I wired the fuel pump relay to see if the fuel system will prime. the relay clicked, but did not pressurize the system. the fuel pump relay signal does turn on my test light for 2 seconds & thens turn off. the fuel pump never primes the fuel lines. questions. would the antitheft pcm feature keep the engine from priming fuel system, cranking and running? is the pcm awaiting the signals of all the connectors such as MAP sensor, coils, Injectors, knock, crank sensor etc. to prime the system. any help I will appreciate it thanks. clark.

[littlevictories]

from what I understand, that is exactly what VATS does
prime the system, then cut out fuel pump supply voltage

[ls1nova71]

If the relay is coming on and then going off after a couple of seconds then it's working. The fuel pump relay won't stay on unless it sees an RPM signal. VATs doesn't have anything to do with the fuel pump prime. If you're not getting power to the pump, then it's the wiring between the relay and the pump, or the ground to the pump that isn't right.

[dec010974]

ls1nova71, good afternoon. thanks for your assistance. well the relay signal, test light, is coming on and shutting off. my problem may be with the wiring of the fuel pump relay. the fuel pump works fine. trust me on this one. I tested it to find leaks in my system.

[dec010974]

thanks ls1nova71 and littlevictories for your replies. just to update you, I completed all my wiring (extending the driver side coil and injectors). I also rewired my fuel pump relay. the engine coughed for 2 seconds, each time around, but never completely ran. this means that I will need a pcm with the vats removed. I bet that will fix my problem. yeah, I know, I should've done that first. I'm sorry. I have so much stuff laying around that sometimes I forget what I have. somehow I thought I had dbw pcm with the vats removed. thanks again for your help. clark.

[truckdude239]

just send yours out to be reprogramsed its only like 100 buxs for a mail order tune

[BR3W CITY]

Originally Posted by dec010974

thanks ls1nova71 and littlevictories for your replies. just to update you, I completed all my wiring (extending the driver side coil and injectors). I also rewired my fuel pump relay. the engine coughed for 2 seconds, each time around, but never completely ran. this means that I will need a pcm with the vats removed. I bet that will fix my problem. yeah, I know, I should've done that first. I'm sorry. I have so much stuff laying around that sometimes I forget what I have. somehow I thought I had dbw pcm with the vats removed. thanks again for your help. clark.

If its possible, I'd think about contacting a local tuner and asking how they handle tunes and specifically how they handle "first starts". Some will allow you to Pay for a "canned" flash (VATS and emissions delete, set VIN etc), but then deduct that amount if you come back for a full Dyno tune. This can be cheaper then paying for a mailorder tune (which has a built in margin of error) and then having to re-tune the truck at a dyno to actually get peak performance.

[dec010974]

BR3W CITY, thanks for the advice. funny you should mention that. I called a few people locally and most of them street and dyno tune. but no one offer tunes to get you running like vats removal, egr removal, fan on/off temps, etc. its crazy to know that no one in Miami, Florida offers this service. and if they offer this service , it will come with a heavy price tag. I called one guy he said he sends this service out to one of his homeboys in Missouri. We all know that this is lt1swap.com. and he wanted to charge $250.00 for this service. super crazy.

[dec010974]

too bad I wanted my pcm by Monday.

[dec010974]

Problems, problems and more problems. im having the same problem I had a few months ago. the fuel pump is not priming. well let me say that it primes when it wants to. I was driving my truck all weekend around the block , testing the airbags. Today I came home and "bang, nothing". I couldn't get that engine to run if my life depended on it. it seems like it primes and works properly when it wants to. By this time Wednesday, it will be back to a carbureted lq4/th400.

[Jon01]

Just spend the $ and have the harness professionally modded.

[BR3W CITY]

I was looking at the third pic thinking "well there's the problem, a bird built a nest in the engine"

[Clyde65]

Originally Posted by BR3W CITY

I was looking at the third pic thinking "well there's the problem, a bird built a nest in the engine"

hahahaha! thats funny right there! I dont care who you are, thats funny!

[dec010974]

Br3w city- Ha, ha, ha. Very funny. LOL. i wish a bird nest was the problem. it would be a lot easier to resolve. thats my pre-wire, to ensure every thing is working proeprly. i would hate to wire everything nice and clean to find something doesn't work and have to re-wire the truck. when i wire my trucks, everything is soldered. stop telling jokes brew city and help me fix my problem.
Jon01-Why pay somenone to do something I can do myself? my first lsx swap, i bought a complete kit from a vendor and i had to completely go through the harness to get it working properly. the coils packs were crossed, the 02 sensors wired wrong, and the tac/foot pedal never worked. the vendors harness taught me how to wire/perform lsx swaps.

[Jon01]

You are seeing why you pay a professional above with all of the issues you are having.
Plus that looks terrible.
I have cut up harnesses in the past. After paying Bill @ BP Automotive to do my last one he will get the rest. Great work, fair price and fast turnaround.

[dec010974]

jon01-I spoke to bill several times. He is a very cool guy. if i decide to go back to EFI side, I will definitley use his services. like i said b4, thats a prewire, to see if every thing works. apparently everything didnt. that why im going back carbed.

[BR3W CITY]

ignore the priming, if you run a hot wire straight to the FP, does the truck run?



*and btw, I will never stop telling jokes. It comes with the territory of being me. Besides, your clearly getting flustered by the project, which always makes things harder.
I do encourage you to not give up on the FI, but it carbed makes you happy, go for it.

VATS pulls spark, but I'm not sure if it pings the coils to see if they are connected. IF there is a constant multiple misfire, or rollover etc, the PCM can shutoff the fuel pump circuit to prevent bathing you in gas and lighting you on fire....I took this feature off, I like fire.
It will allow cranking and might even allow 3-5 seconds of run, if that. Some people won't even get more than cranking.
Another option, if you really want, is to do a stand alone fuel test. You can try another electric pump hotwired, right to the fuel system. The return doesn't have to even go the same place, its just a way to test. Its like the old "gas can above the carb" trick when your tank isn't in yet.

If you want, I'll do the same for you as I've done for numerous members here. If you'd like I'll pm you my number and you can call me and we'll go through it.

[First c10]

When I started my LSX I had the same bird under my hood. but shot him after the motor started!!!! ok no Jokes!!!

Attached is a picture of the basic Bosch relay wiring. This is how I did mine. If yours is the same, when you turn your key on the relay clicks then the PCM is grounding the coil side of the relay for 2 secends but if the relay stays then its wired wrong. If the pump does not start then either no ground at the pump or no 12+ positive at the relay(87)
not sure if this makes sense or not....or maybe i am off my rocker!!!
Good luck!!
Scott

[dec010974]

BR3W CITY- if I direct fire or jump the relay on #85 or #86 on the relay #87 will turn on the fuel pump. jokes are cool br3w city. I, totally, admire and value your advice and wisdom on this forum. you're one the few ppl that I would listen to. pm me your number. ill pay for the call. At this time, I am guilty of one thing brew city, and that's is I should have replaced the fuel pump signal wire in the harness prior to removing the efi harness.
Thanks first c10. im clear on how to wire relays. your way is very different. " my friends, #85 & #86, take power from the rich, #30, and gives it to me, #87. Now I have all the power". that phrase is patented boys n girls. don't use it or you'll be in big trouble.
the funny thing is, everybody sh-- works but mine. I wired countless trucks with stock engine harness and everybody, but me, is on the road. maybe I need to stop working on everybody else sh-- on get my sh-- together.

[First c10]

Ok no worries good luck hope you and brew get it figured out. Please update when you get it going!

[dec010974]

Hello to all. Like I said, It will done by Wednesday, Here it is. It went into the garage under his own power. All I need to do is Play with the Timing, Add some Carburetion, and Voila, we have the recipe for a bad, 1971 Chevy C10. Thanks for all the help for those that chimed in. That is the purpose of this forum. Br3w City, Cheers. the Drinks are on me.

[Clyde65]

Originally Posted by dec010974

BR3W CITY- if I direct fire or jump the relay on #85 or #86 on the relay #87 will turn on the fuel pump. jokes are cool br3w city. I, totally, admire and value your advice and wisdom on this forum. you're one the few ppl that I would listen to. pm me your number. ill pay for the call. At this time, I am guilty of one thing brew city, and that's is I should have replaced the fuel pump signal wire in the harness prior to removing the efi harness.
Thanks first c10. im clear on how to wire relays. your way is very different. " my friends, #85 & #86, take power from the rich, #30, and gives it to me, #87. Now I have all the power". that phrase is patented boys n girls. don't use it or you'll be in big trouble.
the funny thing is, everybody sh-- works but mine. I wired countless trucks with stock engine harness and everybody, but me, is on the road. maybe I need to stop working on everybody else sh-- on get my sh-- together.

Geeesh! dont start being nice to him and compliment him, he is hard enough to deal with normally!!!!


JK, BR3w City is a really good guy and he has helped me a ton. not that i am complimenting him at all, just saying!

[BR3W CITY]

[dec010974]

Br3w city, I guess by the fiery devil, you approve this message?

[BR3W CITY]