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TPI Transplant = Complete

noahrob

noahrob

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Alright guys,

As some of you know I have been putting a TPI engine into my '73 Blazer. I have a thread going about the progess, but I need help.The engine is in and the harness hooked up. I turn the key to the "On" position and sure enough the fuel pump primes and the light on the harness comes on. I turn the key and the engine cranks over, with fuel going to the rail, but no spark. We pulled a plug to test and sure enough no spark. There is only 4 wires (In a connector) going to the distributor and then a connector fromt eh distributor to the coil...so would that be the place to check? Anything else obvious to look for? The oil pressure sensor is hooked up just above the oil filter and has three wires coming from it, two go to the harness and one is extra according to the painless wiring instructions...Interstingly enough and completely unrelated, the oil pressure guage which I have plugged into the rear of the block via some brass NPT fittings isn't getting oil...

Ok guys, impress me with your in depth knowledge and help me figure out how to get my junk running.
 
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Well, first off, Painless huh? Sorry, couldn't resist. :) I know they've gotten better than their reputation from a few years back would indicate.

Saves me the typing:
http://www.chevythunder.com/ses_chart_a3a.htm

Ignore the code junk, if you aren't getting spark, start in that box. First thing to check on a retrofit is to make sure you are getting voltage where you need it, WHEN you need it. Very common to grab a non hot in start wire when it's needed.

Where on the back of the block do you have the sender hooked up? Drivers side, horizontal surface next to distributor that is always used for oil pressure tap?

Kind of surprised about the 3 wire switch. First things first make sure you are oiling as you are supposed to be. (if it's not a new engine and had pressure before, it's unlikely, but possible you've got a real oiling issue) I have a feeling that the switch they gave you is a "later" one that combined the oil pressure switch AND the pressure sender. 3 terminals in a "triangle" arrangement? I'd convert to the 3 wire connector and utilize it (after testing the switch/sender to make sure it's what I think it is) instead of having two different components. I did on mine, made routing the oil pressure stuff easier and cleaner.
 
OK, just to make sure I am calling the right things by the correct names, the first picture is the oil pressure sensor with three wires. The second picture is the two wires on the harness the thing in the first picture connects to. The last picture is something that connects under the plenum but has not couter part on the harness and I have no idea what it is...

Picture 102.jpg

Picture 105.jpg

Picture 109.jpg
 
Ok, first pic looks like the combination oil pressure sender/switch. There is no "sensor" per se. The ECM doesn't care about oil pressure. Two of the three wires control the fuel pump if the fuel pump relay dies, the third wire is the sending wire for the stock oil pressure gauge. Thats the one I consider "good". Otherwise you end up with a unit that looks like that, but two wires, and a second component, the old style sending unit for the gauge.

The two wires you mention are the single ones with the spade connectors?? If that's Painless stuff, and designed for the oil pressure switch, that is some hokey crap and I'd be extremely displeased if I were you. I have a feeling (hope) maybe something else is going on though, as all the other connectors look like stock GM stuff, no reason (besides cheaper) to use those two wires on the pressure switch and not a locking waterproof connector.

That last connector I was just looking at today, I'll go trace it for you and see what it is.
 
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As Dorian stated, be certain that you have voltage at the coil while the key is in "start". Many of the circuits get turned off in that position, to make more current available for the starter.

The ECM isn't involved with creating the spark, so the trouble shooting process isn't much different than with a carb.
 
Cool, thanks...I will start there and see what I can find. If you (or anybody else) think of somethign else, pleaes respond. I am a big fan of "leverage what they know" and not "let's reinvent the wheel"
 
I checked that connector for you. Is there a green wire going into it? Now that I think about it, the only single wire I can think of is for the EGR temp sensor, and I couldn't check where that green wire goes. It heads out of the loom just so you can access that connector, then is back into the loom. I think I can reach my EGR temp sensor, so I can probably check to make certain for you.
 
INteresting. I cchecked the Painless Wirring instructions adn there is no mention of a EGR temp anything...the only EGR thingy is the EGR Valve solenoid located near the bottom of the distributor in the rear. I do have a manifold air temp sensor located on the bottom of the plenum adn a real PITA to get the wire hooked up to...Based on the link you posted earlier I think I will dink around with the wires to teh distrubutor adn from teh dist to the coil...
 
99% sure just by looking at my setup that it goes to EGR.

In my '88 TPI manual for 5 and 5.7L TPI, it shows the EGR temp diagnostic switch wire running to pin C15 on the ECM, with an inline connector. I checked mine, and I've got black on one side of that connector (and that's what color wire terminates at the EGR switch) and dk green on the other.
 
I am so embarrased, but I think just reading the chevythunder stuff...I may have found part of the problem...

http://www.chevythunder.com/fuel%20injection%20elect.%20pg%20A.htm

Half way down (maybe 3/4) the page it shows the external coil with two connectors to it. The first one goes from the coil to the distributor...I have that one on and in place....the second one is power to the coil, which is pretty important...yeah, hmmm...dooh. I do NOT have that one. I am such an a*s! I am pretty steaming mad right now, laughing, but steaming mad...
 
I'm going to go out on a limb and say you need to connect those up. I know I'm taking a chance saying this, but just humor me and try. :) lol

Always ends up being something you assume is too easy to be anything but correct.
 
Geez...next your gonna tell me these Blazer things need gas, or that if I don't take the battery out of the garage and put it back in my truck it won't run right...picky picky pikcy...

Thanks for all the help...I'll post back, no matter how embarrased I am:crazy:
 
I guess that you finally got around to checking for voltage at the coil, eh? ;) Whether you're running TPI or toilet tank technology (carb) , ya gotta have the basics. :cool1:
 
Yeah...all I can say is "dooh" and where the heck am I gonna find that little connector?
 
You got any wrecking yards around? Camaro's use the same stuff, and I *think* that coil is almost universal among chev's that vintage.

I can't recall if that one has an inline connector or not, I'm thinking it does.
 
Oy...just got back from the pick n pull with my daughter (4.5 years old) which was actually a lot of fun. After messing around for about 30 minutes watching the forklifts and skiploaders demolish cars, we started our hunt...lo and behold...a 1987 Camaro...got the hood open and bam after a little looking around, I found the 12v power wire I needed....traced it to the end and dooh...it was cut and the connector went with the engine. HA...
 
Anymore if I see an engine pulled, I don't even waste time looking for wiring/connectors. :(

No idea why they cut everything, it's easy to unplug it and they'd make more money, even if it is a hair slower.
 
I had a moment of brilliance earlier and ran back to the pick n pull and got the piece I wanted out of a some late 1980;s chevy thing...It dawned on met hat GM probably used the same piece of rmore than 2 cars...
 
Cool!

Keep us posted!

My TPI is down again. Doing a cam and head swap in the near future, so maybe I'll get it up and running again in March, and hopefully good enough to start driving it and getting it tuned up for summer...
 
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