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1997 7.3 No Start

3K views 22 replies 7 participants last post by  Tomsantos88 
#1 ·
Hi all, im new to this forum but not new to the 7.3. This is my second one and i just picked it up. Its a 97 CCSB 7.3 with a 5 speed. when i test drove it, it ran a little rough but it does have 250k on it. He said it wont start without being plugged in. I figured it to be a relay and didnt pay to much to it. Got it home, tested the relay, it was bad and i replaced it. still didnt start. went to check the glow plugs and found that the connectors on the glow plug harness was smoked, so i replaced that. still didnt start. checked the glow plugs, had 3 bad ones, changed those and it still doesnt start. Figured it must not be a glow plug side issue anymore, so i replaced the CPM for good measure, still not the issue. moved to fuel pressure, checked pressure through the schrader valve and when cranking it had at least 40 psi so i think thats good. i have checked everything that i know how to check, need some advice on where to go next. thanks
 
#3 ·
The above post is a very real possibility. Low compression is another possibility, if it has eaten dirt at some point in it's life.

Starting at the cheap end and working up, I would load test the batteries, and verify that all cable connections are PERFECT.

Next, maybe a starter, how old is it? Just because it's spinning doesn't mean it's turning fast enough to start cold. That's a total judgement call on your part, but personally, I've been fooled before myself.

After that, might be time to consider a compression test.

Sent from my E6810 using Tapatalk
 
#4 ·
thank you for the input, i have not checked the battery output yet. If i do have worn out injectors, how do i test that? i have not checked my compression yet either, what is a good range to be in?
 
#5 ·
If this issue continues I would check compression and make sure every cylinder is within 10% of one another.
Also 40Psi seems a little low for a DI, so you may have some kind of fuel delivery issue. From what I have read you should see somewhere around 50psi for optimal fuel pressure.
Have you noticed any blow by? maybe to much oil or fuel dumping at the tail pipe?
 
#7 ·
See if you have a slow crank then you have to combat that issue first before moving on. Make sure both batteries are fully charged, at least 11.3 Volts on a multimeter, and sometimes leaving them charged on a trickle overnight will give them the optimal charge. Charging them for a few hours and trying again actually kills the batteries faster. Kinda like beating an amish horse, you can only do it for so long before the damn thing gives up. SOOO step one - be sure both batteries are completely charged, then start cranking. If you still have a slow crank I would look to the starter and see what voltage im receiving. If its the optimal 12 volts then the starter is all good, but who knows...I have seen starters still work but not at optimal potential. If I am correct you should see 55PSI at the bowl. if not then you have a fuel delivery issue, In my mind 40 is to low.
Search the google box and see if you cant find the correct pressure you oughta be receiving for fuel. If you follow through with that and still have a crank no start, Id say bust out the compression gauge and see what your compression ratings are and again they must be within 10% of one another. You should see numbers like 300PSI give or take on a compression test but keep in mind they only need to be a difference of 10% from one another.
 
#10 ·
So a little update. i had the batterys checked and they checked out perfect. the starter motor did not. i swapped it out for a brand new one. did not change anything. cranked a lot faster though. so while it was cranking i shot it with a little shot of ether, started up immediately. checked fuel pressure at the schrader valve for good measure, was showing average 60 psi at idle. i guess i need to check compression now? and my injectors? thank you all for your input.
 
#11 ·
If it started immediately with a shot of ether then I’d say you still have a glow plug problem.
The pcm controls the ground side of the glow plug controller . You’ll need to put a test light on one of the little terminals on the glow plug solenoid, switch the key on and see if the test light illuminates . If it does you’ll then what to check for battery voltage at the big cable connection when the key is off engine off . If there is which there should be then perform the same test over again but look for power on the lug that powers the glow plugs themselves.
Be careful with ether . You can have big problems.


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#14 ·
Is there a way to test injectors?? I always thought you could only run BUZZ tests on them to see if they are operating properly. Orrr run a multimeter on it, but then again without having any knowledge of what numbers one maybe looking for throws that idea out the window.
 
#13 ·
Yeah LongJohn and Blue are correct. These DI powerstroke's need that glow plug relay to work properly. Look for a write up on google for testing the glow plug relay. If that checks out and you still have the issue then its time to check the glow plugs themselves. They may be tired. Again, these are easy to check. If you do have burnt out glow plugs, I highly recommend replacing the relay and plugs at the same time. I also had a issue like this some years back...replaced it all and know my WTS light kicks on and off in seconds, though I still wait a good 40 seconds before starting depending on the temp outside. you may also want to check your valve cover harness and check for burnt out harnesses or bad wiring. Keep us posted.
 
#15 ·
If the glowplugs, relay and wiring have all been tested correctly the injector poppets could be worn. This was the case with my 94 with 250k miles (hard cold starts with white smoke even when plugged in and known good plugs/GPR). You measure the gaps between the injector armature plate and injector body (solenoid removed). New will be about 0.004", while worn is below 0.002" (my 94 were around 0.002" with a couple at 0.0015"). Cheers!
 
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#16 ·
i did not get to work on the truck today but it sounds like i need to go back over the glow plug system. i have already replaced the relay, harness and 3 glow plug that were bad but it still wont fire without some persuasion. Just to double check, i check how much voltage is moving through the relay while the key is on. then remove the connectors for the harness at the valve cover and check the end pins for the glow plugs. Is there anything else to check on this system?
 
#17 ·
The way I would do it, is when completely cool, check voltage at the constant hot side of the relay. It should read battery voltage. ( Hot big post to ground)

Connect your meter to the two large posts on the GP relay. Key off should read battery voltage.

Turn the key on, relay should click. Connect meter across two large posts again, properly working relay will read .03 volts or less. ( Volt drop test)

See how long the GP relay stays energized, without cranking, should be 1/1/2- 2 minutes.

Then, if that all checks out as described, it's time to check at the connectors as you mentioned. If not, post it up and we'll go in a different direction.

Sent from my E6810 using Tapatalk
 
#18 ·
Here are some testing procedures I use (some is redundant from Blue-Truck-Nut97's post):

For checking the injector/glowplug wiring: From each valvecover gasket connection's outermost pins (2 per connector) to ground you should get 0.1 to 2 ohms (indicates good plug and wiring). From each valvecover gasket connection's center pin to each immediately adjacent pin, you should get around 3 ohms (indicates good injector solenoid and wiring). You should not get any continuity from any of the outer pins to the 3 inner pins (indicates no shorts between injector and glowplug wiring). You should also get 0 to 1 ohms from each of the external harness connectors outer pins back to the Glowplug Relay's large terminal on the GP side (indicates good wiring from external connections back to the relay).

To check the glowplug relay (GPR), measure the voltage drop across the GPR's large terminals. While the GPR is active (up to 1.5 to 2 minutes after the key is turned to Wait-to-Start) put your meter leads on the large terminals (one lead on one large terminal and the other lead on the other large terminal). The measures how much voltage is being "lost" across the relay. A reading of 0.3V or more indicates a bad relay. Also, check the relay’s control wires (smaller wires) disconnected from the relay for battery voltage at the Red/Light Green striped wire and ground at the Purple/Orange striped wire (check both when the key is turned to Wait-to-Start).

Cheers!
 
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#20 ·
Hello. I had a 99 model do the same thing. The injectors may be worn out internally. You can check by removing the coil on top of the injectors and measure the gap between the armature plate and base. Needs .002-.004 inches. You can get shims and rebuild kits on eBay. Shims and rebuild is a temporary fix but it got my truck starting. Pensacola diesel has good affordable injectors
 
#21 ·
95 7.3 crank no start... i have replaced the starter ipr valve fuel pump it started ran for 30 minutes bogged down died wont restart. For some reason the drivers side battery ground gets super hot and will smoke I'm thinking the truck isn’t getting proper amperage to crank. Also it will roll white smoke while trying to turn over so im guessing it’s getting fuel.
 
#22 ·
I would have both batteries load tested independent from one another, inspect all battery cables (specially the one that smokes!)for damage/corrosion, and check all battery cable ends for corrosion and tightness. Cheers!
 
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