Hard start hot - IP going?

[kconnair]

84 3/4 ton Suburban "J" engine (sort of). Recently rebuilt .030 over w/ gear drive, block girdle, etc, added 6.5 turbo assembly, 3" exhaust, cone air filter, new 6.5 turbo injectors. Engine was a later (90's) 6.2 goodwrench engine. Older IP - turned up a little. Runs great :) - starts pretty well cold - updated with the '85 up glow system and quick heats (this set is holding up ok). I live in Georgia now, and temps have been in the 90's (go figure).

Just recently had some hard hot starting problems. Cranks pretty well, recently replaced starter and checked all battery connections (I have converted to the 3/8 bolt/nut system) and charges at just over 14 volts. It just won't fire hot on re-starts like after a short trip. Should not need a glow cycle to start given the air temps.

Am I looking at replacing the IP soon? (Maybe real soon) I have a couple of unknown condition spare IPs. I am getting ready to return to Ohio and tow one of my cars back to Georgia.

1) Should I take the spares and appropriate tools with me to replace the IP, and try to make it there and back, or

2) should I try and get a rebuild before Friday? Or...

3) Maybe spike the fuel with some (about 5%) new dino oil for the 1400 mile trip, and hope the pump keeps pumping? (and take the tools and spares)

Thanks,

Kevin.

[john8662]

Have a safe trip. I do feel that you should probably always have the parts and tools on hand to repair as you need to, that way you're almost guaranteed to not need them (because you have them).

The hot start could very well be the IP, can also be a fuel return restriction of sorts, in the form of too much fuel pressure in the tank, etc.

Given a good fuel system, you should be able to bump the engine over and have it run. Even if it doesn't bust off the first bump, it should the 2nd.

Where is your timing set at?

J

[kconnair]

Timing has been super-precision set by ear ;) . It rattles with the cold advance, but just barely once the cold advance shuts off. You can tell it's a diesel, but not a powerstroke. Before I rebuilt the engine, I set the timing with a borrowed snap-on meter, and it sounds about the same as it did then.

Most of the time, it starts just fine warm - just when it sits out in the sun after a short run (<10 minutes) is the time it seems to have "issues".

Thanks

Kevin.

[gmctd]

You've either got fuel problems, fuel drain-back problems, or failing IP - what color is the Stanadyne model number tag, down below the throttle lever shaft, driver's-side?

Pour some cool water over the IP next hot-start, then crank it up - if easy-start, it's the IP

Run some cetane additive and 1/2oz ashless 2-stroke oil per gal fuel, see if that helps over-all running\starting

[britannic]

YMMV, but retarded timing can cause hard starting when hot (HPCA compensates enough when cold), especially when the glow plugs aren't kicking in, or some of them are no longer functioning. Before you commit to spending the $ on an IP, double check your glow plugs and the timing with a meter to rule them both out.

I had a similar problem with my truck after installing a new IP; once I got a meter on it, I found the timing was a too retarded to get it started when it was hot.

Definitely check for restrictions in the return line and also that your fuel shutoff is functioning properly and isn't influenced by heat.


Timing has been super-precision set by ear ;) . It rattles with the cold advance, but just barely once the cold advance shuts off. You can tell it's a diesel, but not a powerstroke. Before I rebuilt the engine, I set the timing with a borrowed snap-on meter, and it sounds about the same as it did then.

Most of the time, it starts just fine warm - just when it sits out in the sun after a short run (<10 minutes) is the time it seems to have "issues".

Thanks

Kevin.

[kconnair]

Thanks for the help. The problem is intermittent. I will just have to try a few things and see what works. I may advance the IP just a hair, & see if that helps. I was planning on adding a little 2 stroke oil for IP lubrication anyway - looks like I will increase it slightly.

Kevin.

[Robyn]

One thing that has not been mentioned. The fuel shutoff solenoid in the pump can get funky and fail to energize when you turn the key on.

The next time it does its little thing leave the key on and trot out and tap the pump on top by the return line with something like the back end of a pocket knife or the butt end of a screw driver and see if the thing will fire off.

The fuel solenoid is just a little mini version of what makes the starter engage and after time and miles these do fail.
I drove in one night years ago with our 86 and the next morning, no go :(
If I beat on the IP it would click in but then the next time it might or might not.

You can replace these easily with the top off the IP. Be sure once you do so that the solenoid clicks when energized. If it does not "DONT START IT"
If you have the mechanism jammed the thing can go to full fuel with no way to shut it down.

Another issue, does this truck have the glow plug inhibit switch still hooked up??

When the truck fails to go does the glow plug system come on ?
The glow inhibit can be defeated easily with a short wire (2inches) with spades on both ends and plug it into the plug that goes to the upper RH rear switch in the head.

A short trip of 10 minutes and then a shutdown and a short sit could very well be enough to require another glow to make it happy.

Give it a go
best of luck

Robyn

[neo]

I have been experiencing what i believe is glow-plug inhibit switch dying. Is this the one that is in the head near the back pass side exhaust valve, opposite the front d/s near cyl 1 exhaust? I am having difficulty getting the glow when I need it. It seems as though it has become intermittent recently, and seems like I need to bypass this "feature." There is also a sensor in the head at the #1 cylinder exhaust position, is this the fast idle sensor? If so, where is the one that sends the signal to the gauge on the dash? Thanks!

Neo

[Robyn]

The LH front sender is the temp gauge
The far RH rear down on the head above the exh man is I believe the Cold advance.
There should be another sensor on the RH head on the top rear if it has an inhibit.
My 91 had the temp sensor in the coolant crossover and the ECM ran the show.
I am not sure if the 89 has this or not.
If your rig has the inhibit switch in the RH rear top of the head just jumper the connector with a short wire with spade connectors.

My 86 Burb had this issue and left me Cold and No go in a snow storm in Spokane wash.
Figured it out and jumped it with a paper clip and got on home.

In fact I think the paper clip and tape were still in it when I sold the truck 5 years later. :D

Good luck and keep us posted

Robyn

[Rytari]

I found this topic by search and deside to borrow it little. i have now same kind of issue... my blazer wont start when engine is hot...

cold engine woks ass a swiss clock, but when i drive some tirp, and stop, i cannot get it back to runninnig without help, first i tougth its electrical thingy,mostly because with cables from anothet car always do the job and truck started asap. I found that only 10.5v comes to IP solenoid... so i make new wiring for it, now i got same as battery, no help... then i arrange more power.. 2 new batteries 105ah 850cca(en) i also change all the cables bor batteries and stater and all groud cables also... no help starter i have chaged already last summer, fuel lift pump also... heads, timing chain and IP i chaged summer 06... what else...

yesterday i made test rung... i drove 30 mins, stop and shut down the noisy thing.. you know :) and try to start it again quicly... and it started, under a 2 second i would say... so i shut down again and wait for 20-30 minutes... now i couldnt get it running... it just rotates without any mark on fire in the fuel or something called ingnition, not any... i make really long start but no.. i wait 10-15 minutes and same again... no.. second time... no... 3rd time it just started... it came to live as soon as i hit the starter...

oh, and if you think something about glows... i got 60g plugs and extented glow cycle, and it makes it every time...

i have no idea what to do next

and btw.. it is 78 blazer... w 6.2 n/a diesel from... maybe 83 or something, old heads had coarse threads on injectors... new replace heads are from 92 pickup i think.. and injection pump is repaired J model from. 89 baron cruiser van, i added some fuel to it... it gives me now 1000f egt:S at full throtle

[Robyn]

Try mixing a couple quarts of engine oil in a gallon or so of diesel and dumping the brew in the tank while you add more fuel to "Thicken the mix"

Let this slosh around a bit with a little driving to be sure it gets into the pump.
Try your shutdown and restart again after the addition of the oil.
If the restart is markedly better it means that the Injection pump is basically worn to the point that the plungers cant make enough pressure to pop the injector nozzles and deliver fuel.

The addtion of the oil will add some viscosity to the fuel and may be just enough to get the little creature to fire again.

When the engine is running the pump is turning fast enough to make enough pressure but under starter only it is lacking.????????

Give it a go before you spend any more $$$$

*** Before you mess with the oil trick, be sure that when the engine will not start "HOT" that when the key is turned on that the fuel shut off is clicking on. You can have a helper run the key switch while you listen at the IP for the click. It should be audible. If the click is not there then the fuel shut off solenoid is not pulling in and is most liekely the problem.
These can be changed easily be removing the top cover of the IP and then changing the solenoid.

WARNING be sure you reengage the linkage correctly when you reassemble the IP. Failure to do it right can result in a runaway with no means to shut it off.
Dont want to scare you but this is important. After you are finished activate the power to the IP (KEY ON) and be sure it clicks on and off when the switch is turned.

I have seen these solenoids work fine and come out after a while and no start.

Give it a go and keep us posted.

Good luck

Robyn

[Rytari]

solenoid is cliking, that i have already tested many times... a aslo add redline every time i fill up...but adding viscosity i havent try yet...

also i have now thinkd about return line... if its restricting flow... can it make some problems...

[Robyn]

Having a return line issue wont stop it from starting but will cause issues.

Did you use the 6.5 injectors?? if so the pop pressure could be slightly out of range for the 6.2 pump.

If the solenoid is clicking then try this.
Set things up so you can do this at home and when it wont start try disconnecting an injector line and install a loose injector in that line and watch the thing as you have someone spin the beast. If it pops and sprays fuel all over then the issue is not the IP.

If you are getting fuel then there is another issue. Check it out and see.

Robyn

[Rytari]

nope this one i have stock injectors...

[Robyn]

Check the thing when it wont start to see if you are getting fuel to the injectors.
You can unhook one line on a LH front and spin the sucker to see if it squirts fuel.

How is the compression???


Robyn

[Rytari]

i dont have anything suitable to check copmression... i have been thinking to modify something for it but... or just buy one, but in here... i dont know where to find

[Rytari]

so i have made some test... i could not be able to test if it gives enought pressure to injectors... i only open one pipe and fuel is coming... but not much.... i also made test while washing my truck... i open the hood and cool the pump with water for some time... it works... i get it running again... but realize that i dint try first if it starts without water, dumbass like me always fogets something

[Rytari]

im getting rebuild pump with bigger size "head" (if i ever will got money for turbo) so i hope my issue is over for now.

[Jambi]

so i have made some test... i could not be able to test if it gives enought pressure to injectors... i only open one pipe and fuel is coming... but not much.... i also made test while washing my truck... i open the hood and cool the pump with water for some time... it works... i get it running again... but realize that i dint try first if it starts without water, dumbass like me always fogets something

Don't be so hard on yourself Rytari, With what you did with your K5 build you've earned a few passes :-)

[Rytari]

Don't be so hard on yourself Rytari, With what you did with your K5 build you've earned a few passes :-)


:D

now you dont know what you are saying... one damn ip is not the only one... my friends call me king midas.. sort of.. all that i drive tuns to not gold, but broken somewhere...