# 97 7.3 diesel starts hard



## Ziob34 (Oct 12, 2005)

got a 97 f350 with the 7.3 getting ready for winter and for some reason its starting hard........what used to start on the first cycle (wait for light and glow plugs to heat up) now takes a good 3 to 4 times through to start. Glow plugs were new last year don't think it is them but could be wrong......any ideas? once its started it'll started up on a dime all day long this problem only happens in the morning when its been sitting all night.


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## Banksy (Aug 31, 2005)

What brand of glow plugs did you use? I've heard the Auto Zone types are known for burning up pretty quick. How new is the GP relay?

I guess it's also possible that you have an air leak in a fuel line somewhere.


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## Plowtoy (Dec 15, 2001)

I bet you have a bad glow plug relay. You can get an updated relay from your local ford dealership that comes with a new wire harness that converts the old style (94-98) to the new style (99-03). I had that problem with my 97 and its quite common. The relay wears out over time and wont allow enough amps through it too the glow plugs


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## FISHERBOY (Aug 13, 2007)

You could change ur oil in the high pressure oil pump, that could help also


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## truckitup (Aug 21, 2011)

I agree with Plowtoy, had a 97 and that fixed the same problem.


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## Holland (Aug 18, 2010)

Dont overlook the simple things, is it turning over good? 7.3's like their rpms for cold starts.. make sure your batteries and all connections are good!


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## FordFisherman (Dec 5, 2007)

GPR most likely, just did mine again. Use a fisher or western they last longer than that Napa junk and cost alot less.


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## Plow More (May 26, 2009)

FISHERBOY;1495447 said:


> You could change ur oil in the high pressure oil pump, that could help also


Thats not any different than changing the engine oil. Get a volt meter and check the relay yourself. Have someone turn the key on while you check the two large posts on the relay for ~12v. It should also stay on for about a minute in cold weather. You should also hear it click. How many miles on the engine and are the injectors originals?


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## brad96z28 (Aug 21, 2005)

Plow More;1495497 said:


> Thats not any different than changing the engine oil. Get a volt meter and check the relay yourself. Have someone turn the key on while you check the two large posts on the relay for ~12v. It should also stay on for about a minute in cold weather. You should also hear it click. How many miles on the engine and are the injectors originals?


True changing the oil in the hp pump that mixes with the regualr oil any way is a big was of time. Also checking to gp realy use an amp meter do not look for voltage is means nothing when checking for amp draw. You can have a bad gp relay that will show 12 v on both sides but is not passing the amps.See it all the time with all types of relays. It should draw around 180 with the correct glow plugs (beru) those are the only brand you ever want to run in them! Any less amps you have bad glow plugs. O to 5 amps bad relay. It takes about 5 min the ck out how the whole system is operating.


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## Plow More (May 26, 2009)

^^^what he said. You just have to open the box and see what brand they are. Dont use autolites mainly. Another thing to check though is the level of the oil in the HPOP resirvoir. Little allen plug in the top of the resirvoir right on top and in the very front of the engine. Stick a screw driver in there and make sure the level is within about an inch of the top. If not, you may have a drainback issue and cranking the engine 3-4 times could be the hpop priming back up before it will have enough pressure to fire the injectors.



How many miles on the truck?


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## dieselss (Jan 3, 2008)

Also. Try to ohm out the glow plugs at the valve cover connector that will tell you if you have a issue under the cover


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## brad96z28 (Aug 21, 2005)

If you do the amp draw test at gp solenoid you dont need to waste time doing that.If you have a 180 amps you know they are ALL working. Unless you are getting paid by the hour or something.


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## dieselss (Jan 3, 2008)

Sorry but how many pple have an amp clamp? Not exactly standard auto tool


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## brad96z28 (Aug 21, 2005)

Anyone that wants to fix a vehicle. Same principle with testing a starter or alternator checking volts and voltage drops does not tell amp output or draw.


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## dieselss (Jan 3, 2008)

So what happens when you don't have 180,,,,gotta do the ohm test so 6 to 1 or half dozen to the other. Whatever you have, whatever is easiest


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## brad96z28 (Aug 21, 2005)

Depends on what you get for amps . Say you had 140 or 160 amp that means you have 1 or 2 out, And that will never even create a hard start problem on one of these systems So you would look elsewhere for a problem. The old non ps engines even 1 being out would cause hard start problems. If you get a 5 or 10 amp reading you replace the gp solenoid, 0 amps ck wiring at the gp solenoid for propper operation wiring checks out change gp solenoid. If you want to ck each gp one at a time the easy way is with a test light at the valve cover connectors.Test light lights gp is good. Its a fairly simple system. I know on the later ones I have had to clear trouble codes after I found the problem for the system to function propperly again.


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## dieselss (Jan 3, 2008)

Well 1 or 2 might depending upon temp but the op never said anything about smoke. 1 or 2 will cause ruff running. If you had 140 amps your still Gunna ck to see which ones are bad regardless. And how many pple ck the amps on a charging system that's operating and 14.5. If you turn on lights and heater and it drops below specs,,why ck amps alts bad. If alts only putting out 12.5. Why ck amps alts bad. And how many pple on this site, have a test light, dvom, and an amp probe.


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## brad96z28 (Aug 21, 2005)

1or 2 being out will not cause a hard start in these temps. If it had a 140 amp draw I would not bother checking them I would want to find out why it starts hard first. Because that wont do it. Changed alot of alternators that put out 14.5 volts but only 25 or 30 amps. As a matter of fact i did one 2 weeks ago on a tundra charging just enough amps to keep the battery light off and had near 14 v running but was getting a dead battery alternaor did not supply enough amps to charge the battery. So I would say mechanics and people that have a clue ck amps.


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## dieselss (Jan 3, 2008)

At 14.5 with lights on and heater on high? No way they put out 14.5. maybe at idle with no load sure but I need load ill agree 1or2 at these temps will not be a hard start,,,but will be a smoking start


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## brad96z28 (Aug 21, 2005)

Lights and heater dont draw what 15 -20 amps thats not enough to make any kind of a test. Voltage while cranking is something you can go by.That bad alternator did not 14.5 as many alternators I check dont it was around 14v I use a carbon pile load testor to see what the alternator does.Some cars have computer controlled where the voltage is lowered by the computer and has nothing to do with the alternator. Yes might see slight smoke at inital start up with a couple or more out. And the only gp solenoids I have used to replace bad ones have been motorcraft with no problems. I have never tried a plow solenoid that is much cheaper.Might work just as good?


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## Milwaukee (Dec 28, 2007)

Easy way to know you have bad glow plug relay is get big screwdriver and short out on 2 big studs. Hold on it for about 30 seconds then go inside truck try crank.


I replaced those with Boss's biggest relay solenoid it been work good.

If it injectors cheaper is switch to 5w40 shell synth it will work best for while.


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## dieselss (Jan 3, 2008)

Ok goes back to...who has shop equipment testers? Lights and heater are a good way to test. 15-20amps only from a carbon tester. Start up amps aren't telling u alt out put if you have low or bad batt,,, a good tech will know without a carbon tester


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## brad96z28 (Aug 21, 2005)

Milwaukee;1495646 said:


> Easy way to know you have bad glow plug relay is get big screwdriver and short out on 2 big studs. Hold on it for about 30 seconds then go inside truck try crank.
> 
> I replaced those with Boss's biggest relay solenoid it been work good.
> 
> If it injectors cheaper is switch to 5w40 shell synth it will work best for while.


Ive had to do that in a pinch.Thats a great free test with extremely minimal tools.


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## brad96z28 (Aug 21, 2005)

I give up .I might as well explain it to the head tech at town fair tire.


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## dieselss (Jan 3, 2008)

Well let's just agree to test our own ways and what works best for them is there way and that's fine. Were here to help and that's why there's 10,000 different ways that pple can get the same results


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## Ziob34 (Oct 12, 2005)

thanks for the input i'll go through it this week i think they were autolite cheap plugs some are probably burnt out any recommendations for good long lasting plugs....got the truck with them in it truck has 190k on it


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## brad96z28 (Aug 21, 2005)

Motocraft/beru only. If it has autolites pray they come out. I have had to take a a few sets of heads off because of people using those.


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## Ziob34 (Oct 12, 2005)

can you get them online anywhere decent price pretty sure i just have a few burnt out plugs.


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## Plow More (May 26, 2009)

Last i knew (couple years ago) autozone carried the good ones at a really good price


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## brad96z28 (Aug 21, 2005)

Plow More;1497964 said:


> Last i knew (couple years ago) autozone carried the good ones at a really good price


Thats correct. The label has some sort of an off brand but looking at the gp its self it should have the beru name on them.


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## Plowtoy (Dec 15, 2001)

I don't get it? Why would you replace something that has already been replaced and is not a real fun job to do, but not replace something that hasn't been replaced and are known to fail and only take 10 minutes to do? I still think you have a bad glow plug relay and suspect you will end up replacing that after you change your glow plugs. JUST MY $.02


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## clark lawn (Oct 7, 2005)

Plowtoy;1498004 said:


> I don't get it? Why would you replace something that has already been replaced and is not a real fun job to do, but not replace something that hasn't been replaced and are known to fail and only take 10 minutes to do? I still think you have a bad glow plug relay and suspect you will end up replacing that after you change your glow plugs. JUST MY $.02


Or better yet do some troubleshooting and find what the problem is before you just start changing parts.

It really hasn't gotten cold enough anywhere yet to need the glow plugs in order to get the truck started.


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## Ziob34 (Oct 12, 2005)

clark lawn;1498308 said:


> Or better yet do some troubleshooting and find what the problem is before you just start changing parts.
> 
> It really hasn't gotten cold enough anywhere yet to need the glow plugs in order to get the truck started.


need the plugs to aide the diesel combustion......several plugs were burnt out put all new in fires right up....


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## dieselss (Jan 3, 2008)

Good deal its fixed and that's all that matters


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## Ziob34 (Oct 12, 2005)

by the way if anyone needs plugs advancedauto has them online motocraft zd11's reasonably priced at a little over 10 bucks a peice with coupon. 

going to buy a glow plug relay later this week to keep on hand just in case....any brand recomendations or ones to stay away from? thanks for the help


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## FordFisherman (Dec 5, 2007)

Use a Fisher or Western plow relay they last longer than that Napa junk.


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## brad96z28 (Aug 21, 2005)

never ever had a problem with motorcraft.


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## clark lawn (Oct 7, 2005)

Like I said already. You more than likely have another issue going on. You don't need glow plugs to get a 7.3 started, or any diesel for that point, until it is below 50 degrees. New plugs may have helped but they didn't fix it.


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## Ziob34 (Oct 12, 2005)

its been below 50 degrees in the mornings for a while now.......new plugs fixed the problem easy starts since.........

on another note anyone ever had a glow plug relay only draw about half of what its supposed to? friends truck plugs all test fine but relay has 12v at the battery post but only draws 6v when you turn the key on instead of the normal 12.


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## brad96z28 (Aug 21, 2005)

I dont ck them that way but sounds about rite, if you did not have any glow plugs working you would have 12 volts. Turn on the key and you got about a 200 amp draw there is your voltage drop. But I ck these with an amp meter to know exactly what its doing.Cking voltage does not tell you a whole lot.


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## wewille (Jan 20, 2009)

Agree, an amp clamp is the fastest, most accurate way to test the overall health of the glow plug system. You can save a lot of time measuring overall current draw before messing around checking individual glow plug resistance. That is like wacking it with a hand full of crushed glass. Where are you measuring the 6v at? The output terminal of the relay or the b+ terminal?


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## Ziob34 (Oct 12, 2005)

all his glow plugs tested fine resistance wise (around 1.5 ohms).....he's getting only a 6 volt output on the relay which i'm told should typically be close to or around the input (12 volts) if the relay is working properly. maybe i'm wrong i suspect he's just got a bad relay thats just worn out and has a bad connection?


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