I've heard people around here complain about the injectors that came on the 89 cars. What exactly is the problem with them? How do I know if I have the bad ones? What would be a good replacement?

Thanks!

 

The Multecs?

They are just more prone to failing. I wouldn't just pull them and replace them just because you have them...unless you have the time and money. But be prepared to buy some (i.e. have a day and ~360$ ready to buy some Ford Motorsport 24# injectors and a adjustable fuel pressure regulator (holley))

Like I said though, if they aren't bad...don't replace them yet.

 

for starters you can use an ohm meter on them.if your not planning on major motor work just look on ebay or keep your eye's open on used ones for replacement IMO.or you can go for Ford motorsport 24lb'ers Ive seen them for as little as $100 on the Mustang forums.used that it

Alan

 

If they work don't fix em. The 24 lb Ford racing are a good choice if they fail. I would buy them new from summitracing.com

 

Okay, I've got an ohm meter, what resistance should I get on the injectors? Is it the electronics that are prone to failure? I have been having a wierd fuel issue which sounds like it could be the injectors! Sometimes feels like the engine is being starved of fuel. What is the #'s for the stock Multecs?

If I do replace them, what makes the Ford injectors so good?

Sorry for the dumb questions. I don't mean to be a noob.

 

Stock for '89 are 22lb. I don't remember the exact resistance specs, but they should all be within an ohm of each other. If one is far from the others chances are it is bad.

 

Ohm meter can tell you if they are failing but not everything. Such things as leaking injectors cannot be told by ohm'ing.

Before doing any of that, have you put a fuel gauge on your rail? (There is a schrader valve for it on the pass side) Hook one up and watch it. It should be steady (I can't remember the pressures for stock now) If the pressure is cutting, I would suspect the pump.

Also, once you shut off the motor it should hold for ~30 minutes. This not happening...can mean leaky injectors, not necessarily though.

Have you ever replaced your fuel filter, though I don't really know your problem it could fit the bill from your simple description.

Also the fords are well liked because of price and quality. They seem to be relatively cheap and work well for a long time.

 

Haven't tried the fuel pressure test. I'll pick up a pressure guage at Azone the next time I'm there.

As for the problem I'm having. It's usually from take off. I'll start to acellerate and all of the sudden it will bog, like it's being starved. I doesn't die, nor does it feel like it's going to die. When I press the pedal more, then it resolves and goes away. It will usually only happen once during a drive but not every drive. The fuel pump was replaced around 25k miles ago. Could probably use a change. Any thoughts?

 

You mean the fuel filter?
You could check it.

Is it full of gas?

 

With the above advice...

I finally had to replace the ones on my '90 because 2 of them failed... ohms were low on one & dead on another. But, I was totally abusing mine after installing a Procharger & FMU. The FMU was jacking my fuel pressure to above 100 PSI!!!! when I would hit around 8 lbs boost. At those pressures, my injectors were locking up, hence the abuse...

I'm now running 42lb injectors I got from Greg @ Blowerworks.net but you won't need that kind of fuel for a stock setup. I then burned myself a custom chip to bring the injector pulse down to where it should be. I've never seen my PSI go above 70 now.

Just so you know, when I killed mine, we were on a club dinner run & I definately knew something was wrong as 2 cyls not firing not only sounds funky but power is way down.

By the way, years ago I had sent mine to TPIS for a cleaning & "blueprint" job. They basically de-scale them w/ cleaner & then any that flow a little low are (I'm guessing here) cleaned a little more to increase the flow & get in line w/ the otheres. My pressure gauge would show they held for several hours after a shut down.

Bottom line, if you do decide you need a couple (doubt that is your prob. though) send me an email, I'll cut you a deal on known working ones.

 

The early OEM injectors, up to 92 (?), were not alcohol resistant. The methanol fuel additive used after 91(?) attacks the epoxy on the coils and causes them to short, eventually.

Not saying that is what's going on with your car. The helm manual has the diagnostic charts for the fuel system. Briefly, make sure the F/F is good. Then do the pressure test on the pump. When the motor is good and hot, shut down and ohm the injector coils. They should be in the 12 to 15 ohm range....I think but check the FSM for the stats. The injectors could be the problem in your case....usually when the coils start to short they give a "miss" and the "miss" gets worse the hotter the car gets. That is the most common sympton of shorting injector coils.


Tom

 

My 88 bogged down at full throttle until I changed my exhaust. A clogged cat or stock exhaust could be the problem. If you had an injector problem I think it would be noticible at any RPM and it would be hard starting.

 

Yep, ohm them and do a fuel pressure test, that should give you an idea about the health of the injectors. If you have the FSM it also tells how to use a vacumn guage to see if your exhaust (cat) is clogged.

 

89corvette: You ask some good questions on the Multec injectors.

Why are there problems with these injectors? the coils of the Multec injectors are cooled by gasoline flowing over them. The coating on the wire used to make the injector coils was not formulated to resist the gasoline and its chemicals. Over time, the wire coating degrades and falls off. This allows the turns of wire to touch each other and short out. As the coils short out, the resistance of the coil is reduced and the function of the injector is also reduced.

How do you determine if you have shorting coils in your car? Remove the electrical connector on each injector and measure the resistance across the two terminals. The reading should be between 16-17 ohms and all eight injectors should be close to the save ohm value. Do this on a cold and hot engine. It is possible for the resistance to be in the above range with cold injectors and out of the range with heat. Heating up the engine may produce shorting coils.

The Multec injectors were used in years 89 through 91 and were discontinued by GM. I believe the use of fuel injector cleaner accelerates the shorting coil problem in these injectors. I had this problem in my 89 and so did two other friends. If you need more info, let me know. Most of this info come from Rich Jensen at Cruzin Performance.

 

Do you mean it should hold steady for 1/2 hour or that it should take 1/2 hour to get to 0.

 

People report different findings, but shoot for holding steady for at least 30 minutes. The main thing you are watching for is for an immediate drop to 0. If it drops a few psi over 30 minutes or very slowly, you may be just fine.

 

Mine leak really bad.
Symptoms for this paticular problem are after you have run the car a while and park it (went to the grocery store, etc) and then try to run it shortly afterward, it will act like it is flooded. The injectors will leak and basically flood you out. If you let it sit long enough, it will evaporate and you can start it right up. The other thing is you can just sit there and crank it until it eventually burns out, but by that time your battery is drained and you will have to jump it

Ive been told many times to replace mine with the Ford Racing injectors, a lot of people also use the Ford Pink Tops. Aparently Ford uses mostly Bosch injectors, and there are several from their Mustangs that fit out cars perfectly.

A new set runs around $300ish give or take.

This is the last thing I need to do with mine to make it 100% with the motor. Then I can focus on the suspension that is falling apart