How hard is it.....?

[DOCTORBILL]

How hard is it to replace and / or fix the Injectors on a '90 Cherokee 4 L straight
six ?

My Cherokee 5 speed manual just turned over 220,000 miles this summer and is
going strong - no oil use or smoke.

Just had the clutch and slave piston replaced.

I would suppose that the Injectors will be the next thing to go - never had them
serviced.

I'll bet THAT is going to be expensive!

Can they be changed by a home garage mechanic with club fingers and a weak mind?

DoctorBill

PS - Where is the ECM (Computer) located on this model?

[MagicRat]

Originally Posted by DOCTORBILL

I would suppose that the Injectors will be the next thing to go - never had them
serviced.

Modern injectors are very reliable and regularly last the life of the vehicle. There is absolutely no reason to consider their replacement until they fail.....if that ever happens.

As for servicing, they really do not need anything. Up to a few years ago, mechanics made lots of $$$ promoting a 'fuel injector service' where the vehicle ran for a few minutes on a pressurized bottle of fuel injector cleaner.

This kind of service is really not needed these days, since fuels are cleaner.

However, if you are not sure, try this first: I personally have had very good success using Lucas Fuel system additive and cleaner, in old EFI vehicles. It dramatically improved my '84 Toyota Supra (160k miles) by removing build - up. But it did nothing for my '97 Cadillac, probably because the injectors were pretty clean to start with.

If you ever have to replace injectors, they are not much more difficult than replacing spark plugs. The trickiest thing is to make sure the fuel lines and o-rings are located properly and do not leak.

[DOCTORBILL]

No kidding!?

I thought (was told by a VW mechanic) that injectors 'wore out' when the orofice
which the fuel sprays out of gets worn larger than it should be and the fuel
just squirts out instead of spraying out (atomizing).

In fact, I had my injectors on a VW Bus changed (for $1,200) because I was
told mine were shot because of crap in the gasoline wearing the orofice too large. About 20 years ago.

I was also told by him that it takes a computer to "reset" the injector timing for
new injectors and to "balance" them....

Did I buy the Brooklyn Bridge ? Should I have my ass kicked ?

Ignorance is expensive!

DoctorBill

[thundergod1320]

Injectors do eventually wear from use. However, untill the spray pattern has gotten really ratty they're generally ok till they get noticably bad (running poorly)
Todays filters are better than the ones 20 years ago... Fuel storage tanks were mandated changed from steel ones to fiberglass. This eliminated much of the rust and debris (and water) we used to buy as an extra along with our fuel, therefore extending the life of most fuel system components in general. I run a small amount of Marvel Oil in my fuel about once a month. Also, you could consider using 2oz of acetone per 10 gals of fuel... at this low concentration it won't harm system, will clean up the injectors and perhaps give you a few more mpg's.

[DOCTORBILL]

Well MagicRat and ThunderGod, I feel much better about my Cherokee now.

I was worried about those Injectors at 220,000 miles from past experience, but if
things are better now (Sounds like something some politician says), I will leave
well enough alone.

However, I bought a slim bottle of Lucas Injector Cleaner ($5) and put it in my
tank today.

Thanks for the advice and information.

DoctorBill