hey guys, I am new to the forum and dont know a lot about tpi systems, but I have a big problem and could use some help. I just finished up a engine swap into my 56 nomad. the car ran fine, except for a problem with the fuel pressure. It was very eratic. I finally figured out that I needed to run the return line to the tank instead of running it back into the feed line out of the tank. but after I got it all back together, It starts, but wont run over a second or two,before it dies. it holds good fuel pressure at about 43lbs, the noid lights fire rite up untill it dies, the dis. retains power all the way through the process. I have replaced the rotor cap. rotor brush, plugs, ign. module . the scanner says no rpm count. it ran fine untill I changed the line. any ideas

 

Did the donor car have VATS?

 

Thats one thing I dont know, but it has been running for a while, I even drove it to two shows.this happened after I rerouted the return line. How can I check to see if vats is the problem?

 

I understand that the fuel or the fire is turning off, but from all the test I have done, I cant tell. But the fuel pressure is holding rite through the dying part, so i am leaning toward the fire. I stuck a used plug in # 1 hole, and it fired strong rite up till it died. but I cant tell if the plug quit fireing to cause it to quit or not. its a new engine, so it dies rather quickley.

 

If it ran at one time then vats is most likely not the problem.
Are you getting any codes?

 

scanner is detecting code for no rpm count

 

What kind of distributor are you using? Sounds like the ECM isn't seeing the ignition pulses from the distributor.

 

Pull the distributor cap and make sure the distributor is actually turning ie no stripped gear.
If ok then check for pulses at the tach wire.

 

the engine cranks and runs perfect untill it dies. I checked for any wear in the dis. but no play sideways and maby .10 up and down . new cap and brush and new module. hei type.

 

So you don't have the computer controlled distributor installed? You can't run a stock HEI dist with the ECM as it needs to be able to control the advance and it needs to "see" the tach signal from the pickup in the distributor. There is no vacuum advance on the stock computer controlled unit, so if you have a vacuum advance then you have the wrong distributor if you want the computer to run the engine.

 

If it ran before then having the wrong distributor is not the problem. If he had the wrong one it would have never ran in the first place. It has to be from a part failing. Maybe a wire was unplugged and never plugged back in when he redid the fuel line.

 

Is the fuel pump shutting off before it dies and does it hold pressure when its NOT running or just when its running? It should hold pressure when shut off.
If so put the fuel line back like it was to start with and see what happens.

 

the dis. is correct, it does not have a vacume adv. it also holds pressure on the pressure guage for quite a while after it dies, thats why I am thinking it has to be fire. I thought it might be the pickup coil, or let me ask a novice question, sence tjhe only thing I changed was the fuel return line, what would happen if I have a partialy blocked line or something? or does the computer have a shutoff if the pressure gets to high?

 

today I'm going to take the return line loose just to see if thats the problem

 

today I took the return fuel line off , and ran it into a bucket, but no change. the engine starts rite up, and runs for about a second, and dies.

 

Will it run if you step on the accelerator? Mine occasionally does what you're describing, starting up but not idling. I just turned the adjuster screw on the throttle body to open it up a bit. If that's the case, you just need to reset your tps and iac.

 

it doesn't matter what i do, it dies like you hit it in the head with a hammer, but it starts rite back up no problem.I've even tried keeping the switch turned to start longer than needed, but it just died. the only code it gives is no rpm signal.

 

hhhhhhhmmmmmm, I thought surely that at least one of you guys had seen this before.

 

code 42 ? you dont state what ecm you are using 1227165 or 1227727 or 730. I didnt see the answer weather your fuel pump runs more than just the 2 sec prime ? At first seeing the post I though the tank wasnt vented but you eliminated that trying to run with the return line off. Drp stops at 400 rpm but you can check the voltage cranking on the purple and white wire dist ref out of the icm or at the ecm. Injectors will not pulse without this tach signal 5v square wave signal.

 

I will check the voltage today hopefully. the pump holds pressure all the way through the process. I'll ckeck to see which computer I used, but I think it is the 730.

 

on a 730 the dist ref is on D8 purple/ white . if the pump just does the 2 second prime only you should be looking at the oil pressure switch / circuit .

 

I was rechecking everything today, and found that my dis. cap dosen't have the center spade going to the coil grd. will this cause the problem?

 

Im not sure what your saying is missing the wire coming from the icm that controls the coil ground ? or are you saying your missing the coil wire that goes to the rotor ?

 

the dist cap has a grd. in the black 3 spade plug the center wire is a grd. is was missing but I put one in and changed the coil and the module , but nothing helped. I've got .5 volts at th purple and white wire, and I checked the coil in the bottom of the dis. and every thing test good. I dont know what else to do, except put a ecm in it

 

Don't these engines ecms require a signal from the oil sending unit to run the fuel pump or do you have it wired to the ignition through a relay.

 

oil pressure is wired through engine harness for the car. The oil pressure switch evidently has been removed from the prom

 

 

At what address in the $8d .bin is the change for the ecm not to receive fuel pump sense 0x24c bit 5 ?


http://www.hotrodlane.cc/newtech/tun...elcircuit.html

 

Does the housing for the ecm have to be grounded?

 

no don't ground the ecm case

 

going to try grounding body tommorrow, and I got another ecm to try. after that, I guess it'll be edelbrock and aluminum intake time, I know without a doubt I can make them run.

 

well , the problem gets more flustrating every day. here's what Ive tried so far


checked fuel pressure and its ok before during and after running.
changed timing module
changed coil
changed ecm
changed dis. module
changed rotor cap
changed,rotor brush


12v to dis is constant ,cranking,running, and dying.
ive got .5 volts to dis on purple and white wire
plugs spark through running and dying process
noid light pulses through process same as plugs
scanner shows 180-200 rpm wheen cranking
scanner shows about 6 degrees advance chen cranking.
put in fresh gas
changed fuel filter
scanner shows no codes

 

If the cranking speed is accurate you need at least 400 rpm to start the engine.

 

It does start and run, so The scanner may be off . I dont knoe how to check it. oh buy the way, I put the dis in a vice and hooked it up to a battery, it sparked really good on all 8. I cant think of anything else to look at. WE even called a GM high perf. teck line,and tried all their suggestions, but no help.

 

this problem totally makes no sence. what am I not checking?

 

I was thinking (I could be wrong) that 400RPM was the threshold where the ECM decided that the engine was running and no longer cranking.

What happens when the ESC wire is disconnected, same thing exactly? I'm thinking that when it fires, the ECM advances the timing a bunch. Since there is no crank position sensor, the ECM depends upon the timing to be set at a known location, hence the 6* you see when cranking.

Outside of that, if the ECM is "seeing" ref pulses from the dist and is pulsing injectors and sparking the plugs when it dies, then it's pretty much down to a fuel supply or timing issue.

Did you try starting fluid to see if it would keep running?

 

I have tried timing at several settings, but no help. I will try force feeding it this morning.

 

this morning I took some berimans, and sprayed a bunch in the pvc hose and it ran to or 3 seconds, so I had a friend spray some in the hose while I was cranking it and it kept running, then it kept runningafter the berimans burned out. it is stil running like crap, but it is running. try to explain that. now it runs like crap as long as the oxygen senser shows lean, but when the senser shows rich, it smooths ouy a lot.

 

How do I post something the website New user sorry the ramdom one

 

Iput another set of new plugs in it today, and set the timing at 38 degrees full advance, and it seems to be running pretty good. but it does run rich untill it warms up.

 

can I unplug the 9th injector without any problems?

 

the ninth injector can be unplugged it is not hooked to the ecm it is controlled during cold starts bye the cold start switch. You stated your are running tpi sd so the ninth injector is not needed on $6e 89 maf and 90-92 $8d calibrations.

 

I thought it might be the reason it is running rich when cold.

 

I thought it was running rich when cold, but the scanner says its lean. it just choakes down and dies, untill the oxy. senser kicks it into closed loop then it idles fine. But if i put it in gear or the fan turns on, it will idel down from the load, and not recover. no codes are showing

 

`drove the 56 to town and back a couple of times this weekend, and it seams to go down the road good, but it still has trouble learing to idle rite. Ive set the idle air control at 1*1/8. and the tps at .65 volts, what else can I do?

 

there is no learn for the idle speed in $8d but there is for definition $88. There will be alot of things that will affect it vss or lack there of, vacuum leak, timing lazy iac, carbon buildup in the iac passage. Have you set the min idle speed ? On a 730 ecm if someone has put a older 85-89 tps with the elongated adjustment slots you could adjust the tps but the range is 0.660VDC to 0.760VDC at idle.
A eprom calibration can affect idle quality as well I have had good luck with some broadcast codes automatics in manual trans cars but it depends on the tune. It is better to start with the closet and newest broadcast code and tune from there.

 

I don't understand the $8d or $88. my ecm is the 165.

 

I'm just giving information off what you provide an there is some lacking. The 165 ecm you will need to set you min idle speed then set the tps to .54 . Disregard the definitions listed your ecm still does not have a idle learn. Is the memcal in your ecm a unmolested factory memcal ? If so what are the letters on the top of the silver sticker ? Is this car a manual or automatic ? are you using a 2k ppm vss ?

 

well, I can drive the 56 now, as long as I slip it up into netural when I stop. I cant find anything wrong with any of the settings, so I must have got a bad IAC unit. How can I check it to see if its working?

 

Not sure if you have a 700r4 but if you do and go into lockup it's not a vss issue. If you can datalog you can watch the iac and vss. you can test the iac commanded movement at idle with a iac noid but its just a bipolar led with a 1k resister on iac 1 and 2 coil.[/U]