Hey all ...this is my 3rd idi and I thought I had a good handle on these things but this one has been kicking my rear since I picked it up.. First was the killing glow plugs , now this...
So just to point out some strange symptoms. It's been sitting for years but I have ran it here and there and now back to working it out.. But since I picked it up it always had this strange sound at idle.. Kind of a faint up and down change in rpm..
I had air intrusion problems I guess before Hopefully fixed ,no visible fuel leaks...new tank ,fresh fuel,recent filter, no factory water separater..
Recently changed a few return lines an injector cap and o-rings
Also has a new lift pump because because I thought the volume output was suspect.
Also has a new starter so this thing cranks like mad..
Ok so just prior to the lift pump I started experiencing the no throttle response thing... It would range anywhere from a completely lifeless pedal to a slow responding increase in rpm..
Toying with the throttle when it's acting like this , "stabbing it" would result in a stall... So now every time I push the clutch in and let off the pedal she'll stall..
I thought for sure I cured it when I did the lift pump but it's back..
Injector pump is new territory for me but my guess is that my problems are somewhere in there or the plumbing..
Also when it is running it's pretty smooth,no missing and no smoke....so ....leaving me scratching my head at this point...
Ran it all last night in the recent snow storm...went to start it up this morning and gave me the old air intrusion symptoms...fired quick then died... 9 degrees.. Figured it was just cold ... Haven't been able to get it going yet.. I do have fuel at the injectors... Got it on the heater now ...see if we can eliminate glow plugs..
Sooooo....mush mash of info I know....not sure if this is all related or I have several things going on at once... Will post back after this thing has been plugged in for a few hrs....
Appreciate ideas...

 

Ok so 2.5 hrs on the ol factory block heater and she fired up like nothing ever happened..6 seconds on the glow plug button, low 20's.. Besides throttle/fuel problem , I'm thinking I may be down on some glow plugs.. Check it this weekend

 

Well the answer is multiple problems... So aside from the lazy throttle, I managed to kill all the plugs....crazy as I've been using the truck for a while now.. It has to be some sort of engine condition hurting these things...I'm not sold its electrical..
Looks like I'm going to be ordering the timing tool and possibly swapping his pump out....

 

I've been battling similar issues and after all I changed. It ended up being the fuel supply line. I was getting fuel to my e pump but had alot of air bubbles. Not saying it's your issue but I had no visible leaks or anything like that. I dropped the fuel tank and fixed the fuel pickup tube. I did new orings and return kit. E pump instead of the mechanical. Clear return line. Delete the vacuum switch on top of the fuel filter housing also deleted the Schrader valve. The only thing I didn't change is the fuel return line to the fuel tank and the injector pump. The last thing I changed was the fuel supply line and success no more stalling or sluggish issues. Even with the e pump I stabbed the pedal and she stall on me so I know your frustration

 

Thanks for the reply!!!
Maybe I should give the clear line trick a shot before I go to crazy...
I have just been assuming that if I had good flow at the Schrader valve that I was good..
So if I am correct your saying your clear line is on the output of the ip and you deleted the check valve? I think that's the part a guy on YouTube was finding debris in.???? See if I can find it in your posts..
Thanks again

 

Most people install the clear line from the check valve to the injector under the fuel filter hosing. I replaced my check valve but some people have deleted it. With the clear return line install on the check valve going to the injector under the fuel filter housing you will be able to see any air bubbles in the line if you havnt replaced your check valve then that could be it. It's a common part to fail

 

delete your glow plug controller and replace it with a manual push button to actuate the relay ..

replace the relay while your at it - less likely than the controller but the contacts in there can also fuse closed ..

your glow plug system is sticking on - and burning all the plugs out ..

it's not mechanical .. it's the GP controller or relay ..

glad u got it goin ' though ..

alternately you can delete the glow plugs and start off ether ..

engine will be damaged if you use ether while a glow plug is warm ..

at a minimum replace the GP relay and plugs and install a momentary push button ..

best regards and good luck ..

 

Thanks for the reply... Unfortunately I've been down this road before and this was one of the reasons the previous owner bailed on the truck..
Currently is a known good relay from Napa, ford beru plugs, controller completely unhooked(ground and plug) the only thing that is still hooked is the factory dash light on the plug side of the relay...I've been very careful of my on time...6-8 seconds.. And this last time they died...I'm pretty sure it was before I ever jumped it...
I guess anything is possible..but I find this crazy cause I know of other pre 87 6.9's where they were running the"junk " plugs and one with an operator who would hang on the button for what seemed like an eternity and no problems...I'm trying not to be closed minded to this but I feel like I have ruled out the accidental "on too long condition"....
But I will double check that relay...ya never know...
Thanks again

 

I'd try to get a working controller and 8 good glow plugs. Fix it up right, and the controller will keep you from frying glow plugs.

I recently got the first IDI which had a controller that actually /works/!
It starts right up, first try, every time, at 20F. I can hear the controller staying on for a good 10-14 seconds, which seems like a relatively long time... but it works!
One glow plug died on me a month or so ago, and it didn't work nearly so well anymore. Took like 2-3 cycles to get it to start, and it only stayed on initially for like 6 seconds.

So, considering it's A, working nicely, and B, I'm still running the Champion glow plugs that came with the truck(which are pretty crappy compared to Beru, and /will/ bulge if you get them hot enough)... I'm utterly amazed, and thinking that perhaps there *is* something to having a controller instead of a push button.

 

sorry to hear about your glow plug woes ..

glow plugs are unreliable and for this reason i don't use them and only use ether ignition ..

but if you insist on using plugs and you continue having this strange and unexplainable difficulty with them .. i would look into AC Delco 60G's ..

they are continuous duty for humvees for the 6.5 but can be modified ..

people use them to build smoke machines with dc converter and they are left on ..

here's a link to a guy that has modified them thus ..

this isn't my page or work .. and i cannot verify of validate any claims ..

but it's a known good perfoming glow plug and he seems to have cut them to fit .. here

diezelcrazeesidipage-acdelco60gplugs

good luck - hope u can get it worked out ..

i'd hate to replace glow plugs all the time ..

also .. another way to do it .. if you want to ditch the plugs ..

is disconnect the glo plug relay ..

link together spray can straws and run them in through the grommed in the firewall under the dash along with the wires ..

drill a tiny hole in the air cleaner and simply connect an ether can of your choosing and have a reliably starting engine ..

either way .. good luck with it ..

 

I hear what you are saying and my 86 utilized the factory controller and cheapy plugs till I drove it to the bone yard..As much as I don't want to keep throwing money at glow plugs, I'd really like to figure this out ...two controllers and a manual setup later and still same trouble...

Thanks for the reply....not quite ready for the ether setup yet and thanks for the heads up on the alternative plugs..
On a side note been running the truck all week long on the block heater and a sniff now and then... Been starting fine and no troubles air intrusion wise...so baffling... Haven't had time to tinker with this idi mainly cause my daily driver(97 f150) is drying out in the garage suffering from gem issues and a leaky windshield.. Always all at once...
Still need to solve the poor throttle response/stall thing...
Thanks again for the help gang

 

I have to say...
I had to loan my blue '88 to a friend for a few days. It just hasn't wanted to start easily though.
I put a new controller from Autozone in it, no real change(though the Autozone controller has /far/ less electronics inside it than the factory controller... for better or worse).

Just checked today... 3 dead plugs. Replaced them with Motorcraft ones from O'reillys.

Massive difference - WTS light says on for like 15 seconds now, and it fires /right/ up, first crank. Just like my 93. So, that might be the secret here - modern controller and good glow plugs.

 

Aside from the glow plug issue, My lagging throttle response is back..
Used the truck throughout the spring and summer with no troubles, figured it was just something that cleared out. But its Back !!!


And its not that she isn't making power , if I accelerate up hill in 4th even though she responds slowly , she will get there and start pulling.


At this point I feel like I need to get back and make sure all this timing and cold advance business is working correctly not to mention warm operating temp( t stat), cause basically this started up as it got cooler, maybe just a coincidence ???
The other funny and new symptom is an occasional delayed reaction to "key off", she will continue running for a short moment instead of instantly killing the engine...
First step is I am going to do some research and figure out checking these solenoids, and confirming operating temp.

 

Really check that you are getting fuel pressure to the IP under load, and there is no air in it.
A little bit of air will cause this sort of thing - "starving" for fuel. Unlike a gasser, it won't choke or anything, just... not have as much power.

Cold advance and high idle only affect it when it's cold; up to operating temp and you only have the shut-off solenoid in play.

Check if it happens longer with the blower fan on max and less/disappears with it's off.
While it /shouldn't/ happen, depending on how things are wired, the blower fan will become a generator as it spins down and keeps enough power to the solenoid to keep it energized for a few seconds... IF it's not isolated by a switch which I THINK normally happens.

 

Sounds like you have an IDI....