Replacing Injector #8 in 94 Q45

[joecz]

Injector #8 on my 94 Q45 is toast - infinite resistance, while the rest of the injectors are at 12.8 ohms. I also checked #8 directly on the injector terminals to be sure it wasn't a broken wire. I appreciate all the info posted here and on q45.org regarding injectors but I have some questions none the less.

Looking at #8, it seems to me that it can be replaced without removing the plenum. Is this correct? Can anyone offer thoughts on the best way to go about it? (I've replaced the fuel pump based on the instructions posted on the old forum- that's representative of my skill level - I wouldn't be confident removing the plenum on my own...actually it's the getting it back together that I'm not so confident about)

One problem that I can see from the start is how to drain the fuel rail so that I don't flood the cylinder when I remove the injector (that is, if I can remove the injector). Dealer price to replace that injector is $900, so any help would be appreciated.

[99q45t_vl]

I can't speak for G50, but in my experience to relieve the fuel pressure I had to remove the pump fuse, crank it couple of times, and then remove the fuel cap. I still had some gas going in the cylinder so I had to suck it out with the hand pump from Advance.

[sdkhalsa]

To drain out the residual fuel, rev the engine moderately and then pull out third fuse(15 amps) down from the top right on the panel to the left of steering column. Next, wait a minute and crank engine for about 5 seconds. Repeat this about three times and you will be all set. Typically, engine will run a little on these later sets of cranking. Once, out of curiosity, while I had a fuel pressure gage t'd in, I noticed that just pulling the fuse still left about 15 psi in the line but that by going through the remaining cranking of the engine, it came down to zero.

I can't speak for G50, but in my experience to relieve the fuel pressure I had to remove the pump fuse, crank it couple of times, and then remove the fuel cap. I still had some gas going in the cylinder so I had to suck it out with the hand pump from Advance.

[joecz]

Any thoughts on if I can get #8 out without taking off the plenum?

[cccpman]

I dont think so, on my 90 the fuel rail (and thus injectors) are directly below the plenum. I tell you what, Q45.org has a good writeup but I ran into so many problems today it seems like it wasnt worth it to replace a injector and both KS (but maybe when she is able to start up I will feel differently)

[goody90q45]

Any thoughts on if I can get #8 out without taking off the plenum?

You can easily get to #1, #2 and #8 injector without removing the plenum. You'll be laying on your belly to get to #8 but it's very accessible.

There's many different ways to remove an injector. Sounds like you've read a few posts so you should have an idea of how to go about it. I use a pair of screwdrivers as levers to pry upward using the indent on each side of the injector and apply steady pressure. It will eventually pop out. Good luck.

[joecz]

I wanted to report back that I successfully replaced the injector. Took 1/2 hour to get the old one loose (vice grip) and put the new one in (Scottsdale). But even though I had pulled the fuel pump fuse and ran the engine to stall, followed by multiple cranks, enough gas still got into the cylinder to hydrolock it. So I had to pull the #8 sparkplug to blow the gas out, and that took another 2 hours. Really felt bad I didn't have new plugs on hand after all that work.Thanks to all for the help, she's riding fine again.

[Q451990]

Just out of curiosity, did you remove the gas cap after you did the pull-the-fuse method to release the fuel pressure? I found this out the hard way while I had my first Q torn down in the driveway, waiting for parts. I went outside to find a stream of fuel trickling down to the curb. The expansion of the fuel in the closed tank from the sun was enough to cause a lot of it to push it's way under the hood. Good job catching it and not letting everything hydrolock. T3 has a lovely c-shaped piston rod hanging up (former tech) as a reminder not to hydrolock a Q.

Heath

[joecz]

I removed the gas cap before pulling the pump fuse. And, I cranked it a good number of times after it died. So, imagine my surprise when the engine went "thunk" instead of starting!

By the way, for those trying this at home, here's some details of my experience..... besides the injector, you need 2 new o-rings and a new rubber bumper that presses down on the injector inside the cap that holds the injector in place. Two screws hold that cap in place, one was easy to remove, the other refused to give in for the longest time and the Phillips slot in it was destroyed in the process (bad design to not have used bolts here). To get the injector out, I grabbed onto the flat sides tightly with a large visegrip (there is just enough room for it at injector #8) and slowly rocked, pried and pulled. It came loose suddenly and as it came up, the plastic tip surrounding the end of the injector (now brittle with age) impacted the edge of the opening and broke into several pieces. Luckly for me none of the broken pieces fell down into the cavity. So, be careful. Clean out the cavity before installing the new injector. There wasn't a lot of crud, it was very clean - much cleaner than I expected - but there was some residue from the old o-rings that was worth removing. Lube the new o-rings with Vaseline and the new injector slides into place with force. I used the cap to get it in the last 1/8 inch. Not recommended, I know, but it worked out fine and got it fully in place.

This was not hard at all; if it wasn't for the gas that leaked in and the time consuming project to get it out, I would catagorize it as an easy repair. Saved me over $600 by searching and asking my questions here.

[AlabamaDan]

Quote »Saved me over $600 by searching and asking my questions here.[/quote]I think we could all say something like that. I've saved more than that. You should put that in your signature. Glad you got it fixed. I really dread the day I have to get under the plenum. Pulled one at a junkyard once - what a lot of work. Can't imagine doing it on my own car where I cared about the hoses and stuff.

[Q45tech]

Remember the fuel pressure regulator will stop drain fuel back to tank when rail pressure drops below 35 psi and the intake fuel damper and check valve on pump will stop around 20 psi so the rail can only be pressure relieved via injectors or front rubber connecting hose.

All fuel hoses should be changed regularly and frequently since they are not rated [SAE grade] for ethanol.............. luckily 10% only creates slow destruction and sloughing.

Changing 1 injector means all have been exposed just the weakest one failed first.

If you think about it # 8 is the first in fuel flow 8,6,4,2,1,3,5,7 then return to tank.