Hard starting,photo eye in injector pump bad?

[bjdem]

1994 6.5 turbo suburban, hard starting, seems like it wants to go, but then doesn't start. lift pump is suppling fuel to the injector pump, but i didn't test the fuel pressure. A Mechanic said that the photo eye in the injector pump can go bad, said it cycles 8 times and then switches to default to let the engine start. Any thoughts about this? Does this make sense? I changed the fuel filter also. It seems harder to start after it has been sitting over night or for a day or two, but sometimes I will stop for just five minutes and it will be hard to start also,but not always. Mechanic wants to put in a new injector pump, I don't know enough about this problem or his explanation. Any help would be great!
Thank you

[MTTwister]

Caveat - don't know from nutin' - but - could it be a flakey shut off solenoid? that's the cylinder on the top of the pump - looks like a nice "handle". This is what shuts off the fuel flow on engine shutdown. Might be somethig on checking that in the member's area.

When it runs - does is stall on you? if on cruise control, does the cruise drop out randomly? - that could be a bad PMD ( FSD when remotely mounted. )

[Hubert]

Hmmm whats the overall condition of the truck milage performance etc?

Verify good fuel, good cranking speed, glow plug operation,and fuel to injectors before changing IP. All easy checks.

Recent fill up? Its easy to get a bad tank of fuel. Anything odd in the filter bowl. Sample fuel and let it sit in clear container any separation?

Does it sound like its cranking fast enough? ie batteries good? You could jump start it for reference.

Multi meter or test light as many glow plugs as you can reach. Summer time if a few work you are ok.

Loosen an injector line drivers side front is easy to reach. It should weep fuel cranking it.

How does it run warm? Performance? Does it run smooth very soon after start up? Any codes or check engine light?

You can tap the fuel shutoff solenoid if its sticking and sometimes get it to free up. A fuel additive cleaner/lubricant might help too but fixes in a bottle are questionable.

[bjdem]

Thank you for your replies, MMtwister, Hubert
Suburban has 170,000, already have remote PMD, does not stall after start up, Mechanic tested the injector pump/photo eye check out ok
glow pulp seem good, gauge moves on dash when light is on/off
good fuel to injector pump, did not check pressure
Changed fuel filter and added fuel injector cleaner, last two days no problems, starts right up
Check engine light does come on when driving up incline, goes off if I let up, stays on if I keep accelerating, some black smoke too, Probably a seperate problem
Again any thought? Much thanks!

[tom.mcinerney]

Maybe just had clogged filter....

Good place to start with electronic engines is check diagnostic codes, no need special 'codereader' for your '94 which is 'OBDI'. Technique illustrated at the Kennedy Diesel site's 'Tech Tips':
http://www.kennedydiesel.com/6265techtips.html

The battery-starter cable is critical on '94.

Some reading:
"Turbo Tips No Start, Stall, DTC 35 or P1216"
accessed at:
http://www.thedieselpage.com/members/tt99-9.htm
{will require your usr name/pswd}

also: http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=004386

maybe:
http://www.thedieselpage.com/members/guide.htm