Engine/Transmission (1994 - 1998) Intermittant hard starting at operating temp

[BSMcCauley]

I never have a problem firing my my 1996 when cold. The "wait to start" light goes out about the time my pre-lube pump has developed 30# of oil pressure, I twist the key and she's running about the time the 2nd injector fires. However, I have been having a more frequent problem with sometimes having having to crank for what seems like forever when the engine's at normal operating temp. Actually, it is closer to 6 or 8 seconds, but when you are used to less than 1, it seems like it's NEVER going to start! If I get too impatient, I can raise the throttle off idle and it will spring to life with a blast of thick black smoke out the tail pipe (immediately dissapearing to normal). Runs just like the day it was new other than the intermittant hard start @ 0 throttle when warmed up. Anyone got any ideas?



Details on the truck: 1996, 4x4, auto, bone stock engine except for the 12V pre/post lube, 202500 miles on the dial. Besides normal maintenance, it's had the thermostat upgrade, KDP secured, recall throttle cable replaced, rubber return hose replaced (cracks caused hard COLD starting problem). Factory Tach indicates about 750-800 RPM at idle whether A/C on and in gear or not. Fuel economy remains 24. 5 @ 1500 RPM (ignore the spedo 'cause it's too depressing) or 19-21 @ 70-75 depending on traffic and load. I'm usually empty, it's my daily driver -- 65 miles across Houston twice a day. The truck's got a couple other mods that are not drive train related.

 

[REFLOYD]

does it do it at the first start in the morning?

if so it is the same thing as mine probably. get a tach and check the rpms at idle mine was idle way to low took it to the diesel shop here they hooked their tach up to it and it was actually at 650 even though the factory tach said about750-800 idled it up to 800 and now no problems...

 

[DieselDoghouse]

I see by your signature you've replaced hoses so an air leak - loss of prime is less likely, and should affect your cold starts anyway from what others say. Here's my 2¢: Check the boot on your shut off solenoid in case its cracked and admitting water. Corrosion on the plunger kept hanging mine when the solenoid was physically warm (metal expansion) so I didn't have full fuel. The problem started VERY subtly and I founght with warm starts just like this (progressing to no starts) for months. New boot from FosterTruck, dry lube on the plunger and its been like new.

 

[BSMcCauley]

Thanks for the tip! I had actually wondered from time to time about the fuel shut-off solenoid -- but more from an electrical point of view. Never thought about a mechanical problem with it. I'll check that out. For any others interested, it will probably be a couple weeks before I get back to this, so stay tuned until then...

 

[BSMcCauley]

Mystery solved!!

Crank-forever-before-starting problem turned out to be electrical after all. Turns out that the starter apparently has plenty of power to roll the engine at 6 volts -- hot or cold, but the kill-the-fuel solenoid won't pull in at that low of a voltage very reliably. Problem surfaced when I went out to start it one morning and all I got was that stomach sinking clickkkkking noise from the starter coupled with the radio and everything else blanking out while the key was turned. Replaced the batteries with fresh ones, and starter now pretty much rolls the engine at nearly idle rpm and haven't had any trouble out of the fuel shut-off solenoid since. Now the question is, Why did I only have trouble before with the engine warm? You would think the battery voltage would be lowest when sitting all night and rolling a cold engine rather than just being charged and the engine warm. HHHMMMM! Point is, problem is not solved. Thanks to all for their input!!



Merry Christmas!!

 

[BSMcCauley]

Wonders of spell check! It won't fix words spelled correctly, but used incorrectly. Last line should have said: "Point is, problem is NOW solved. "



Sorry for any confusion!