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98 GMC quit @70mph-no start
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Willybill
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Apr 9, 2010, 5:23 PM
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98 GMC quit @70mph-no start
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1998 GMC K1500 5.0L 144,000 miles, The plugs and wires were changed 4 months ago.Quit going down the road and had to be towed. It would crank, but not start. I ckecked the plugs for spark and didn't have any so I checked the distributor cap and rotor and they needed to changed. After changing them I had spark at the plugs, but it still wouldn't start. It cranks over 3 or 4 times then almost stop before turning over 3 or 4 more times and do it all over again. My son thinks it jumped timing.
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Hammer Time
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Apr 9, 2010, 7:14 PM
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Re: 98 GMC quit @70mph-no start
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That would be very unusual for that engine. I would first get a fuel pressure gauge and test the fuel pressure. This is a high pressure system and requires a minimum of 55 PSI to even run. The pumps fail quite often.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
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Apr 9, 2010, 7:43 PM
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Re: 98 GMC quit @70mph-no start
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If you have zero pressure after running HT's test, a backyard trick you can try is to get a good sized block of wood or dead blow hammer & beat on the bottom of the tank (being careful not to damage the tank) where the fuel pump rests. If it starts that would confirm a bad pump.....
If it does start.....don't drive it, replace the pump, it will just stranded you again.............
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Willybill
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Apr 15, 2010, 5:18 PM
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Re: 98 GMC quit @70mph-no start
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Thanks, Hammer Time & Sidom, it took awhile to get a pressure gauge, it tested at 60 psi while cranking and didn't start The pressure slowly drops, it takes awhile to get to 50 psi. The camshaft and crankshaft sensors have been changed. There is voltage to the ign. module is about the same as battery voltage. What else is there to ckeck for?
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Hammer Time
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Apr 16, 2010, 2:27 AM
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Re: 98 GMC quit @70mph-no start
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First check for spark. If you have spark, try spraying some starting fluid into the intake and see if it fires for a moment on that.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Willybill
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Apr 16, 2010, 3:09 AM
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Re: 98 GMC quit @70mph-no start
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Yes, there is spark and it does fire with starting fluid.
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Hammer Time
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Apr 16, 2010, 3:15 AM
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Re: 98 GMC quit @70mph-no start
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Ok, that narrows it down to a fuel problem. If you are sure the pressure is maintaining from the pump and the fuel itself is not bad, then we have to concentrate on the fuel injectors. Check all your fuses carefully. You may need a scan tool to see what the PCM is or isn't doing.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Willybill
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Apr 23, 2010, 6:56 AM
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Re: 98 GMC quit @70mph-no start
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After reading other posts I decided to check the distributor gear and found it to be very worn. I am in the process of putting it back together. I know #1 cyl. needs to be at top dead center, but how do I know if it is on the compression stroke without taking the valve cover off on that side? I can't see the timing marks because of the AC and power steering pumps and bracket. If it stops raining because its not suppose to be raining, I'm going to work on it today.
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Hammer Time
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Apr 23, 2010, 8:57 AM
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Re: 98 GMC quit @70mph-no start
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There are no timing marks because the timing is not adjustable at all. The distributor synchronizes the rotor and the Cam sensor and it requires a professional scan tool to get the distributor set correctly once removed.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Sidom
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Apr 23, 2010, 7:44 PM
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Re: 98 GMC quit @70mph-no start
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Everything HT said is correct.......
I'm going off memory here so take it with a grain of salt...... Some 5.7s still have timing marks under the water pump and some don't...... Take a look, if your's does then this should work....
Pull #1 plug & bump the engine over until you feel compression coming out of hole. Then put a ratchet on the crank and roll it over to TDC on the marks. Now the dist is ready to be put in.....
Were gonna back up just a bit for a sec..... Some 5.7s had a factory white line on the dist & intake. It was on the backside so you would need a mirror to see.....If yours has one you're in luck. If your replacing the dist put a white line on the EXACT same spot at the old one.
Ok back to the install, look down at the dist and on the plate somewhere you should see a 6 and the over a bit an 8. Face the rotor tip at the 8. Lining up the 2 white lines between the dist & manifold set the dist in and this should set it to #1. You can verify but looking in the cap and tracing where the #1 wires goes into to cap and where the #1 electrode is. The cap is a weird design but you'll see what I mean. If the distrib doesn't go all the way down then the oil pump drive isn't lined up. you can either pull the dist and use a screwdriver to line it up or what I do and just have someone bump it over (not crank) until it drops in. Then just bring it back up on compression and make sure the rotor is pointing at the #1 electrode. Line up the 2 white marks and you should be good.
No white lines and you will need a scanner that shows the cam retard PID to set the timing. If it's off it will set a P1345. You can't use the marks on the balancer, that won't work.....
(This post was edited by Sidom on Apr 23, 2010, 7:50 PM)
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Willybill
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Apr 24, 2010, 12:38 PM
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Re: 98 GMC quit @70mph-no start
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Have been working at getting the dist. to drop into place for the last 4 hr. Got any secrets?
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Hammer Time
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Apr 24, 2010, 1:14 PM
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Re: 98 GMC quit @70mph-no start
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Once you get the teeth in the gear started, hold a steady pressure down and have someone bump the starter. The cam gear and the oil pump drive never align together because the distributor turns as it drops. You'll have to estimate where the rotor is going to land when all the way down to pick the right tooth.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Willybill
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May 1, 2010, 8:54 AM
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Re: 98 GMC quit @70mph-no start
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Well, its been a week since I had a chance to work on the truck. I have a job 4 days, 10 hours a day, and a little rain some wind and flurries and time goes by. Having difficulty with the gear on the end of the distributor lining up with the oil pump, once I got everything in its proper place it did go together quite well. It was just as Sidom said, all the marks were there. I had not seen the 6 and 8 before you told me, the 8 was not real clear. The truck starts right up and idles good. I just hope the new gear is better than the old one. Thanks for the help, this is a great site.
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nickwarner
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May 1, 2010, 9:23 AM
Post #14 of 14
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Re: 98 GMC quit @70mph-no start
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thanks for posting the fix, and glad your truck is back on the road
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