Tis a little hard to start, DS4 pump diagnosis, Dealer Time?

[john8662]

OK,

Been troubleshooting the 96 Tahoe for less than stellar starting in the morning, and when hot outside, pretty much every time you start the thing.

It never pops off and runs with the flick of the key, takes one long crank or two long cranks to get it running, followed by white smoke (if not touching the throttle).

Things done:

-Tested lift pump at idle (rig running) got 5-6 psi at the water drain T
-Replaced fuel filter, and housing with new housing (old was too nasty to clean)
-Replaced ALL the glow plugs with AC-60G's, was starting on 4 11G's
-Installed FSD cooler with NEW FSD mounted for testing (starting unchanged)
-No injection pump related codes
-New starter
-Pretty new batteries, ditched the wally-world batteries it came with (first UPGRADE)
-Improved side terminal connections...


Temps at night don't fall below 70 degrees, average day temp is usually 98 degrees, this thing should start no problem!

I'm thinking tired injection pump at this point, but what do you think? What have I missed here?

I have not run a compression test, not much blow-by, don't think compression is the issue, but who knows (it's USED!!!)

I took a gander at the pump when killing the EGR stuff and it read 5288 with a white sticker indicating sometime in 1996, hmm, looks original, PMD looks untouched as well (plenty of crap on it).

The rig has right at 104k miles on it now, and could sure be under warranty, dealer says no, but I'll show them the doc again.

So is this the pump? Made an appointment with the dealer on Monday to drop the piggy off (hope they don't find the PCM).

One code present (need to re-check though) P0231 "Fuel Pump Feedback Circuit Low Voltage" So I replaced the relay I dropped during fuel filter service (manually make pump turn on with a shunt wire). Don't know if code came back, VatoZone wouldn't clear the code for me (liability, blah, blah, blah).

[JohnC]

John:

It sounds like a worn pump, but, my 5288 pump went 115K miles with no issues when I traded it. YMMV.

Also, 4 11g's will start at least as fast as 8 60g's ;) You might want to tey JK's Quickheats.

Any fuel leaks on the feed side of the IP?

Oh, yeah, retarded timing can make it slow to start, too.

[DmaxMaverick]

All else being equal, 60G's at 11G glow time can give you starting issues. The 60G plug requires at least twice the glow time. Kennedy Quick Heats will solve that problem. Otherwise, you'll have to extend your glow cycle by one method or another.

Also, if any other part of the system is weak, weak glow plugs will just add to any difficulties.

My '85 will start easily with minimal smoke in the summer, without any glowing (manual glow only--no controller, ambient temp 90

[john8662]

Update!

Just went to VatoZone again to borrow the code reader to see what's new and if my other code went bye-bye.

Well, the old code is gone (PCM change most likely) but I do have an anticipated code present a P1214 (offset error).

Needs timed...

I don't think that the pump timing offset is going to have THAT much of an effect on the starting ability, it was poor before all the replacements, still is poor, but seems to be getting worse, the hotter it gets outside. Seems to start better in the morning than it does in the evening sitting hot.

Hmm, gotta think this one through. If I take it to the dealer, they're gonna nail me on the timing and charge me for the time to set the timing even if it still starts poorly after it's set.

Sure do want some bi-di scanner software right about now...

Thanks for the suggestions on the QH plugs. It might be a worthy task to gather up a set of 9G's and install them temporarily to see if that helps it out starting wise, that'll tell me if I need to invest in a set of QH's for this rig...

Trouble is though, once started it runs fine. But, after warmed up and I kill it, then let it sit for 10 or more minutes, then I have to do the two crank session to get it going. It will start up immediatly after being shut off though. So, I don't think it's a glow thing in that situation.

I will do the final fuel system pressurization this weekend when everything is cool (like I did in the 6.2 forum). Didn't enjoy the fuel filter housing re-oring earlier this week with a hot engine!

[DmaxMaverick]

Whether your issue is glow plug related or not, that possibility needs to be eliminated. More often than not, it's the simple things that come back to bite you. By your description, my first guess would be the plugs, or the activation of same. If you your timing is off, weak glowplugs will exaggerate the condition.

[rameye]

John...mine had similar issues...always had to crank it twice to fire it off.

Replaced everything under the sun.....finally I got the dreaded code 19 and the pump gave up the ghost.

New pump now pretty much always starts before 1 revolution.

Dont give up ...get that timing into spec..