Shake Rattle and Roll, Starting and Driving

I have a 99 suburban 350 4X4. When it has set for awhile (4 hours or more) It will start and run fine for the 5 mile trip to town. After getting groceries, gas or whatever. The starter turns the motor over for a second or two then grinds like the motor is locking up or something then reingages. After trying several times I let it set for 30-40 minutes. It started but still with some grinding. So then driving it home. It chugged uncontrollably and didn't want to get up to speed, and it sounded like the entire exhaust wanted to rattle its way out from underneath. With an almost backfire sound at times. This has happened three times in the last two days.
I've got good spark, good oil pressure, and good fuel pressure. All are well above the manufacturers minimum standards. I am getting a flashing SEL when it acts up, but I'm afraid to drive it back to town to be checked. Any thoughts?

With the engine off, ignition on, what does the fuel pressure do when you turn off the ignition? If the pressure drops quickly, the fuel pressure regulator may be bad.

//2000CAYukon

With the engine off, ignition on, what does the fuel pressure do when you turn off the ignition? If the pressure drops quickly, the fuel pressure regulator may be bad.

//2000CAYukon


It drops slowly.

Well the fears came true. I drove it to town this morning to have a CPU dignostic done. The further I drove it the rougher it ran. Got to the auto parts store and shut it down. Got the typical 430 and 300 codes. Went to start it up and bring it home. The engine turned over for a second or two then the starter started grinding. I let it sit for about an hour, and turned the engine by hand a litttle, just to make sure it's not frozen. Same results with the grinding starter. So now it sits until I can drag it home. Any more thoughts, I'm farely certain I chewed up the starter.

Well the fears came true. I drove it to town this morning to have a CPU dignostic done. The further I drove it the rougher it ran. Got to the auto parts store and shut it down. Got the typical 430 and 300 codes. Went to start it up and bring it home. The engine turned over for a second or two then the starter started grinding. I let it sit for about an hour, and turned the engine by hand a litttle, just to make sure it's not frozen. Same results with the grinding starter. So now it sits until I can drag it home. Any more thoughts, I'm farely certain I chewed up the starter.

you appear to have a few problems ..replace starter and mark flywheel rotate and file damaged teeth ...adjust if necessary the starter with shims to get 1/8in clearance between starter teeth and flywheel teeth...

remove the passengerside O2 sensor and with the hole open test run the vehicle..miss fires and this 430 dtc may mean the cat converter is plugged if so the engine will do as you described..

another quicker test in addition would be to start the cold engine and with one hand on each converter see if they both heat up at the same rate and time...I suspect the passenger side cat will stay cold longer than the driverside..

you appear to have a few problems ..replace starter and mark flywheel rotate and file damaged teeth ...adjust if necessary the starter with shims to get 1/8in clearance between starter teeth and flywheel teeth...

remove the passengerside O2 sensor and with the hole open test run the vehicle..miss fires and this 430 dtc may mean the cat converter is plugged if so the engine will do as you described..

another quicker test in addition would be to start the cold engine and with one hand on each converter see if they both heat up at the same rate and time...I suspect the passenger side cat will stay cold longer than the driverside..


I have remedied the starter issue. (FYI the shouldered nurled bolts have to be used. My local autoparts gave me some generic off the shelf bolts, and the starter was jumping around.)

Now that the starter issue is finished, The vehicle won't even start now. With or without the O2 sensor(s) installed. I've tested the fuel pressure again, and all seems well. I have plenty of spark. Any other thoughts?

I have remedied the starter issue. (FYI the shouldered nurled bolts have to be used. My local autoparts gave me some generic off the shelf bolts, and the starter was jumping around.)

Now that the starter issue is finished, The vehicle won't even start now. With or without the O2 sensor(s) installed. I've tested the fuel pressure again, and all seems well. I have plenty of spark. Any other thoughts?

the fuel pressure with the 350 is 60-65psi ...the spark should be blue.
if this is all good ...the ECT engine coolant temp , could be out of cal and this will cause a hard cold start..your problem before was it would gradually run worse..with missfires..now no start..put some fuel in the intake, if it starts then dies this would be fuel ...if it still will not start then this may be the ignition module..at the distributor...

if you had no spark this could be the crank position sensor..

disconnect the MAF connector, then try to start, this is sometimes a problem as the air temp sensor is in the maf...

[quote=Robbinsgang;6095085]I have remedied the starter issue. (FYI the shouldered nurled bolts have to be used. My local autoparts gave me some generic off the shelf bolts, and the starter was jumping around.)
quote]

what happened to the original starter bolts? did they sell you a starter for another vehicle and because it is a different starter you need different bolts...

I never had to change starter bolts before ,,,though I did have them try to sell me the WRONG STARTER !

[quote=Robbinsgang;6095085]I have remedied the starter issue. (FYI the shouldered nurled bolts have to be used. My local autoparts gave me some generic off the shelf bolts, and the starter was jumping around.)
quote]

what happened to the original starter bolts? did they sell you a starter for another vehicle and because it is a different starter you need different bolts...

I never had to change starter bolts before ,,,though I did have them try to sell me the WRONG STARTER !


Well I had a small change of events all at once. First of all when the motor stopped turning over on start. The right side catalytic converter plugged up enough to create to much back pressure on the engine. When I tried to start. The back pressure locked the motor enough to break a starter bolt. Swapped out the bolts with new, and shimmed the outside bolt with 1/16" shim. So it would give better contact, since the starter teeth had gone through a bit of grinding. (Starter problem solved) Next I replaced cap, button, plugs and wires. This allowed me to get it started with no 300 code, but it was still running rough after it warmed up with a 430 code. (multiple misfire code solved) I then pulled the O2 sensors and drove about 15 miles. Aside from the occasional firebelch through the O2 holes. It was running good. I cut out and installed two bolt on cats. With everything back together, and two 20 minute trips. I have no SEL issues, and everything seems AOK. Thanks for the help gang! (Case solved)

so the excessive back pressure from the plugged cat converters caused the starter bolts to break ! amazing stuff...

make sure you have the proper mixtures/fuel burn to avoid damaging these new converters...hopefully you have replaced the defective part that caused all this cat damage.. good luck..