Wont start

[Dansubtruck123]

Hey, so I have a 94 diesel suburban and it wont start, we have had issues with cold starting for a long time due to our glow plugs not working what so ever, but it does start and we have gotten it started in very cold winters with the block heater plugged in all night. The funny thing is today I tried to start it and it wouldn't start, it would crank, (a little slower then normal) and it sounds like one cylinder is catching but none of the rest are, the same thing happend to me last weekend. I thought it might be lack of rpm so I connected a 3red battery to help with crank however nothing happened

 

[Will L.]

Welcome.

DO NOT USE STARTING FLUID. It can destroy the engine id done wrong, and even if done right it forms a crystalline structure on the glowplugs ruining them.

What is the rpm while cranking- it is critical. Next starter you buy- powermaster 9052 incase that is this time.

ONLY glowplugs to use AC Delco 60G. There is a special tool to remove glowplugs if they swell up- NEVER just break them off and run it. You will hear many people- especially from military saying it is ok, it isn’t and I can show you pictures of destroyed engines to prove.

If using the block heater works, then the glowpugs should make it start also- if this is the difference then you need to test/ repair the glowplug system.

When replacing glowplugs this time or the next, instead of one at a time, remove all 8 and do at least a compression test and prefer also a leakdown test. This becomes crucial info later if you have more issues hard starting or poor running. Note it takes a higher pressure gauge than gas engine compression tester.


on the fuel side- take a sample from the ffm drain and let it sit a while then examine.
replace the ip return line (1/4” diameter about 5” long) with clear tubing available at any hardware store along with 2 new clamps. This is a $5 cost that takes 5 minutes max and tells if air intrusion is occurring via bubbles flowing while cranking. Also shows contamination like water and such. Also shows when fuel is flowing through the ip in no start scenarios. Most folks leave it in place permanently- but it needs replacing every few years once clouded from uv light or gets brittle.

A fuel pressure gauge tapped at the ip inlet becomes a priceless tool- I suggest a dash mounted gauge. Low lift pump pressure not just adds to hard starting and dropped power & m

 

[MrMarty51]

/\-/\-/\-/\-/\- YUP, what He said.
Welcome to thetruckstop Dan.

 

[Husker6.5]

Did your block heater burn out/cord go bad? As far as glow plugs go, if all of them are not working, start with the fuse and work the circuit forward from there.

Also NEVER, NEVER cycle the glow plugs with a battery charger attached in Boost or Start mode! They are designed to operate at battery voltage (11.4-12.6 V) and battery chargers in high output mode (100A or higher) will put out in excess of 15V and will fry them. This is true with the old 9G and 11G plugs, and I had the lot boy at the dealership in Mooresville, NC where I bought my Burb fry out a set of Delco 60Gs in my Burb, by trying to start it on a 20° morning to warm it up so it would "start easy" when I got there by cranking the batteries till flat (he had no clue how to start a diesel and ignored the Wait To Start light), then getting the "bright" idea to haul out their big-ass wheeled charger and tried starting it off of its 400A Start Mode (Ignoring the warning sticker next to the Passenger battery about not starting off of a charger that he hooked up to the Driver battery). As soon as the key hit the Run position as he turned it, POOF! We has to plug in the block heater and let it sit for a couple of hours and then it finally fired off. I replaced them when I got back to Lincoln with a set of the original German Bosch Duraterms (ten years ago) and have had no problems with them since.

 

[JMJNet]

It needs fuel and heat.

Fuel, make sure there is fuel flow from the Lift Pump (LP).
On a 94, the LP is controlled by Oil Pressure Sender (OPS) when engine is running.
So, if the part that control the LP is bad, the LP will not run as engine catches, hence it will not start.

Then there is the PMD which controls the IP.
PMD needs electricity on-going, although it is not as much as GPs.

The heat comes from GPs.
GPs need electricity to glow.
So if batteries are bad, then GPs will not even glow and who knows what other things being brought down.
Check the fuses also.

Then the STARTER needs to crank the engine.
Again, this one needs electricity.
After the batteries were used to glow the plugs, it then needs to crank the starter.

I hope this gives you the principle of what needs to be checked and why.
Of course, there are a whole other parts which is part of the system but this is the basic.

 

[Rockabillyrat]

Does it puff white smoke when your cranking it? If it does then that's a good indication that you have a glow plug or compression issue. If there is no smoke then you have a fueling issue. That's the fastest way to narrow it down.

A amp clamp is hands down the best way to check your GP and block heater. Takes 1 min to confirm both are working and pulling proper amperage. And you dont have to disconnect anything to test. Takes the guess work out of diagnosing them.