85 cold start injector replacement
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
You will have to have a custom chip burned. Since you have not listed your location....you will have to go mail order unless there is someone near you that can turn the 870 chip.
The cold start injector is only used on start up. Unless it has died (new 9th injectors are not available any more) I would just let it be. If you change manifolds that don't have a provision for the injector....why not stay with what you have. If you remove it, then the custom tune would just give the 8 injectors a little more fuel at start up. And your going to pay some extra $$$ just to get the new chip to add fuel.
The cold start injector is only used on start up. Unless it has died (new 9th injectors are not available any more) I would just let it be. If you change manifolds that don't have a provision for the injector....why not stay with what you have. If you remove it, then the custom tune would just give the 8 injectors a little more fuel at start up. And your going to pay some extra $$$ just to get the new chip to add fuel.
Last edited by John A. Marker; Jul 4, 2015 at 12:01 PM.
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
You will have to have a custom chip burned. Since you have not listed your location....you will have to go mail order unless there is someone near you that can turn the 870 chip.
The cold start injector is only used on start up. Unless it has died (new 9th injectors are not available any more) I would just let it be. If you change manifolds that don't have a provision for the injector....why not stay with what you have. If you remove it, then the custom tune would just give the 8 injectors a little more fuel at start up. And your going to pay some extra $$$ just to get the new chip to add fuel.
The cold start injector is only used on start up. Unless it has died (new 9th injectors are not available any more) I would just let it be. If you change manifolds that don't have a provision for the injector....why not stay with what you have. If you remove it, then the custom tune would just give the 8 injectors a little more fuel at start up. And your going to pay some extra $$$ just to get the new chip to add fuel.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Your issue is not the 9th injector then if you have to squirt starting fluid or gas into the plenum to get it started....there are other issues.
First get a fuel pressure gauge and test your fuel pressure. It should be up around 36 PSI or more if you turn on the key but don't start the car. Does it hold pressure for 10-15 minutes or does it drop like a rock with seconds?
Check the fuel pressure regulator. Pull off the vacuum hose on the fitting on the side of the regulator and look for fuel in the hose.
Report back to us on what your find.
First get a fuel pressure gauge and test your fuel pressure. It should be up around 36 PSI or more if you turn on the key but don't start the car. Does it hold pressure for 10-15 minutes or does it drop like a rock with seconds?
Check the fuel pressure regulator. Pull off the vacuum hose on the fitting on the side of the regulator and look for fuel in the hose.
Report back to us on what your find.
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Fuel pressure is good and everything else is good.......it's the last thing on the list...I've read every post in the forum here and everywhere else...it's the only thing left...my grandpa is a mechanic and has been collaborating with another guy around here...they can't find anything else...more ideas are welcome obviously...would it crank but not start if there's a little rust in the gas tank...new pump and sender is ok...I just need to narrow the problem down and we have arrived at the 9th injector problem...is the temp sensor bad if it always thinks it's cold? That is something I've been thinking but I'm not sure how the sensor works...I'm glad you're responding tho because I've gotta fix this
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Even if you disconnect the electrical plug from the 9th injector, it will still fire, it will take 2 or 3 cranks to fire.
Did you also replace the filter sock on the new pump? Was there a filter sock on the pump when you replaced it.Have you replaced the fuel filter?
What kind of fuel pressure do you have at the rail? It should be 36-39 for the 85.
Miles on the engine?
Original fuel injectors? Or has someone replaced them.
Is this car new to you? Or have you had it for awhile and this issue is just manifesting itself now.
Did you also replace the filter sock on the new pump? Was there a filter sock on the pump when you replaced it.Have you replaced the fuel filter?
What kind of fuel pressure do you have at the rail? It should be 36-39 for the 85.
Miles on the engine?
Original fuel injectors? Or has someone replaced them.
Is this car new to you? Or have you had it for awhile and this issue is just manifesting itself now.
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
78000 miles with not original but not new injectors...took the plug off and it won't fire...ever...the pump is new along with the sock...new fuel filter installed...the injectors aren't leaking and the ohms are all consistent where they should be...I bought it a month ago and it sat for 13 years...I emptied the bad gas and replaced with new...it used to start every now and then but now it's just nothin...
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Also when it starts it runs like a champion...I can drive it wherever and nothing knocks or misfires but if I shut it off it won't start again...like it thinks it's cold or something and it decides not to spray more fuel...why is it acting like its the dead of winter even when it's just been run for 30 min
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Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
This is a tube/hose that's basically under the oil cap and it goes to nothing...nothing is hooked up right here as you can see...what's this supposed to go to...it's connected underneath to the right somewhere but idk what it is...just realized it might be important
Passenger side
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
I gave my 85 FSM to my some when he got my 85. Tube is in the passengers side.....correct. SO this is all from memory. Check you smog pump...air pump. There should be hoses off of it that swing over to the passengers side to a couple of valves (like 2" around). It seems that there was a hose that connected to a tube like in your picture. There is also a tube like that which points straight down toward the ground the picks up clean air to feed the air pump.
Back to the fuel issue...
You said new injectors at some time....did it sit for the 13 years with these "new injectors"??
And your are getting 36-39 psi at the rail and it is holding correct? I would attach the fuel pressure gauge....spray fuel or starter to get it going...then shut if off and watch what happens to the pressure. When you turn the key back on what happens to the pressure? Does it build or is it non-existent?
Back to the fuel issue...
You said new injectors at some time....did it sit for the 13 years with these "new injectors"??
And your are getting 36-39 psi at the rail and it is holding correct? I would attach the fuel pressure gauge....spray fuel or starter to get it going...then shut if off and watch what happens to the pressure. When you turn the key back on what happens to the pressure? Does it build or is it non-existent?
Last edited by John A. Marker; Jul 4, 2015 at 08:38 PM.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Does your grandfather have a noid light tester kit? It sounds like you have fuel. But your not getting spark...questionable. A noid light would test the injectors pulse.
I understand your confusion and frustration. If it runs, then it should start...but it is not.
I understand your confusion and frustration. If it runs, then it should start...but it is not.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
This is a tube/hose that's basically under the oil cap and it goes to nothing...nothing is hooked up right here as you can see...what's this supposed to go to...it's connected underneath to the right somewhere but idk what it is...just realized it might be important
Passenger side
Passenger side
Last edited by Cliff Harris; Jul 5, 2015 at 02:08 AM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
That is the divert tube with a muffler on the end and air comes out of it when the A.I.R. system is in divert mode. The intake for the A.I.R. pump is on the back of the pump.
Last edited by Cliff Harris; Jul 5, 2015 at 02:08 AM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Also when it starts it runs like a champion...I can drive it wherever and nothing knocks or misfires but if I shut it off it won't start again...like it thinks it's cold or something and it decides not to spray more fuel...why is it acting like its the dead of winter even when it's just been run for 30 min
The cold start injector only works during cranking. It times out after 8 seconds and will not work if the coolant temperature is over 95°F. If it is disconnected cranking times will be increased but the engine should start eventually.
Last edited by Cliff Harris; Jul 5, 2015 at 02:09 AM.
Thread Starter
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Thanks for your input...would the car trying to use a rich mixture to start every time prevent it from starting? It cranks and sounds normal but just won't start...after trying and trying it just won't...I've also read something about the ignition coil going bad in the 85s...think that's relevant here? And how would I check that to see if it's faulty?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Thanks for your input...would the car trying to use a rich mixture to start every time prevent it from starting? It cranks and sounds normal but just won't start...after trying and trying it just won't...I've also read something about the ignition coil going bad in the 85s...think that's relevant here? And how would I check that to see if it's faulty?
There was a problem with high output coils. The fix was to replace it with a standard output coil and reduce the spark plug gap to 0.035" (from 0.045").