Hi guys, haven't posted in a while, hope everyones been good!

So on my 91 club wagon, recently did a full tune up.

New injectors (brand new not reman) and new IP.

Did this about a month ago, already put on about 3k on them, and just this passed weekend I did a 900 mile trip vacation and on the last 400 miles, hauled a big 460 extended van I bought for parts.

About 3 hours from home, when I got off the hwy for fuel, noticed a really bad shake at idle and miss fire.

Drove home like that, and just diagnosed it now, found fuel sipping out of injector line #5. I taught ok just a loose line, tighten it, fire up, no change.


Now with engine running, if I loosen the line, engine smooths out....

I replaced that one injector with another brand new one.....no change? It's puking fuel like it should when I crack it open, but engine only smooths out when it's cracked open?

The hell can this be? Stuck valve or...???

Thanks guys!

 

Swap two injectors. That'll tell you if it's the injectors; you could easily have a metal shaving sticking one open or something odd like that.
The real solution is to get yourself an injector pressure tester(like $150 or so on Ebay), so you can check the spray pattern, leakage, and pop pressure... once you can do that, it's not too big of a deal to disassemble a sketchy one and clean/re-shim it if needed.

 

I have replaced the suspected injector with another one, didn't change anything at all.

 

I forgot to mention, doesn't smoke at all, just a light puff of black on start up (cold or warm) like it's always done.

 

sounds like something is wonky in the injector pump sending way too much pressure to #5

 

I second that. You said it gushes fuel from #5 when cracked, but it should never gush. Should go squirt, squirt, squirt. Produces a tiny amount of fuel at idle.

 

No it pukes out the same amount as any other line I crack open, not puke I should say but rather squirt.

I'm gonna do a compression test on it tomorrow and see what that gives, then pop off the valve cover and have a look in there.

Could an injector pump actually send a wrong amount of fuel or pressure to just one hole....? Didn't think that could happen.

 

No ...

-Enjoy
fh : )_~

 

So I just got the valve cover popped off enough to see inside (still got the 4 injectors to remove to slide up and out) and everything looks good inside, nothing broke or missing.

I fired it up just before tearing in to it and with the air cleaner off, had a nasty loud thumping noise coming from the intake.

Did a compression test on 3 cylinders, all had the same, just over 400psi including #5.

 

I will be interested to hear what you find. I have a slight shudder that developed with mine. Seems to be much more noticeable sitting stopped with it in drive. I was thinking that it was an injector/pump issue for me since I am rolling up on about 100K miles on them and my mpg have dropped some. Also, since mine seems to mostly clear up when the rpm's raise slightly by putting it in park or neutral I though maybe the low stall converter I put in was pulling the rpms down a little more than before.

I know you said it doesn't appear to have any different fuel flow characteristics than the other injectors, but maybe it is off a little. Since replacing the injector did nothing, perhaps swapping out that injector line? At a minimum doing so could eliminate fuel delivery from the equation.

There is always the old ATF/Fuel additive in the filter trick that could loosen up something thats sticking. I know people have different opinions about Auto-RX, but it could be worth a shot to try. I personally know a number of people with other vehicles who have had good luck with it over time. It doesn't instantly fix build up issues, but over miles/time it seems to work well.

 

I'v had the injector return caps crush on me or whatnot. Tighten the **** out of the line and it still leaks. Swapped out with an old one I had laying in the bed and problem solved

Just something to think about. It's an easy check

 

Found the problem!


I got 3 blown lifters, all on the passenger side head.

#3 intake, #5 exhaust and #8 intake.

#8 is totally shot, takes barely any effort to push down the push rod.


#5, my problematic cylinder actually had the best lifter of the bad ones..... but that's the cylinder that was causing my shake... but that one is the exhaust one that was bad so I guess that's why?

Also found alot of silvery metallic stuff on the GP in #5, same thing as when I took my compression probe back out of #5 came out with alot of silvery metallic crap on it.... compression checked great? Should I worry about that?

Any recommendations for new quality lifters? I was thinking rock auto.

Should I do new push rods to?

 

I would go with rockauto just to save some dough.
They carry two options. $7 or $15 a piece! Adds up quick (:

 

Before replacing the lifter, disassemble it!
They come apart easily once you remove the snap ring, and then you can try to find what failed. You may be able to just clean the ball and reassemble it... if it works, then I'd be thinking about cleaning /all/ of them and seeing about trying to get crud out of the oil system(I've heard you can add a little diesel to the oil, idle the engine for a minute or two and then drain it all to help remove crud - or there are products to do the same thing).

If it's not just a matter of cleaning, it still would be nice to know /why/ they failed. They are incredibly simple devices.

 

I will take em apart but I'm not reusing them, if you ever worked on a van, you never wanna do the same job twice, so I'll replace all of em to make sure I don't have to go in there again.


And the inside of this engine is literally shinning clean, I really don't think they failed due to dirt or crud inside the engine. But again, who knows.