clueless in Miami

[dec010974]

As the title says, I'm totally clueless. a buddy of mine has a swapped
5.3/700r4 into his 1994 chevy 1500. the swap was completed a while back. he ran into a stalling problem. he says, when the vehicle is cold, its hard to crank/run. he starts by vehicle, crank/run, by activating the fuel pump for a few seconds (5-10 seconds) turns the ignition, the pcm/fuel pump, primes the fuel rail/system, he turns the key, and starts the vehicle. I know this sounds crazy, but it is. I am like, WTF. he says he has problems starting the vehicle if he doesn't add the extra fuel. I told him that GM's design, of the fuel system, is almost flawless. why would you wire your vehicle like this? he says it works. I think he is asking for trouble. I told him, THE PCM IS smarter THAN he is and doesn't need assistance from you. I think its something in the tune, bad gas, dirty injector, or something else. need advice. I checked all the ignition sources. all sources have power such as maf, injectors, coils, O2 sensors, etc. I check all the connectors, grounds, cam sensors crank sensors, etc. give me some ideas. thanks in advance. clark. BTW,when I was there to check vehicle over, help him with his PROBLEM, it didn't START with his TRIED and true method either.

[BR3W CITY]

This post reads like a schizophrenic having a conversation with himself

Lets break this down and see if we can sort it out;
A] The actual problem is that his truck is hard starting from a cold start (meaning first start of the morning, not ACTUAL cold, since your in Miami).
B] Your friend turns his ignition to key-on, which then primes the fuel pump (and turns on gauges etc). Then after a few seconds, he goes to start the truck as normal.

Do I have that correct?

The first thing I'll mention is that I also prefer to go key-on first, then start the truck. I don't run any sort of check valve in my fuel system, so after a long enough time (overnight) the static pressure in the rails will bleed off. This in no way prevents the truck from running. My truck cranks over immediately regardless if I do this or not, but I choose to because I don't run an NSS for high idle.

Now on to diagnosing is actual problem; In the tune there is something called ASE, or After Start Enrichment. This basically causes the ECM to give the injectors a little bump in pulse width ,essentially the same as priming a carb. If his enrichment amount was messed with, he may have difficulty starting.

It this engine built, does it have aftermarket stuff, who tuned it?

[dec010974]

Hey BR3W CITY. Thanks for your reply. Better explanation: My buddy wired a manual on/off switch to activate his fuel pump. Before he cranks his truck/swap with the ignition key, he manually turns on this switch. It's crazy. I saw him do it. This switch adds fuel or turns on the fuel pump which, adds gas to the fuel rails. He feels his swap starts better this way. He states that this procedure helps his truck starts quicker. He sometimes experiences false starts or the vehicle just cranks until the motor catches and run. i asked him, what's wrong with the PCM controlling this function. I feel that there is something needed in the tune. He has a mail order tune from II,.@$$)(;:/-. Any help is greatly appreciated. BR3W.

[BR3W CITY]

II,.@$$)(;:/-.
I can't begin to decode what thats supposed to elude to. PM me if you don't wanna post it plain text.

There is no reason for his external switch. Just putting the fuel pump on a relay of of the ign switch does the exact same thing (and its how you'd run an electric pump on an older vehicle).

If its dying or not catching, there is something else going on. A vehicle that has frequent failed starts should be tossing a code, possibly a misfire hit, knock, MAF code, crank or cam sensor failure etc. If there isn't a mechanical cause, then either the ase is wrong, or something else was changed in the tune thats causing an underlying problem.

There's more going on here than we know. Was he using the truck normally before he decided to wire in this switch?

[dec010974]

&:$:!.'ek is the name of the person who Mail order tuned the PCM. I made the harness from a stock 5.3/4L60e harness. Knowing him, he switched some things around and probably wired something up. When he said the truck was having problems starting, I told him let me look at it when I get a chance. He couldn't wait and wired up am fuel pump switch. BR3W I'm sure you were the rest goes. When I check it again, I check for diagnostic codes. Thanks for the insight. BR3W, the man. BR3W, the sultan of swat. Deuces.