Does the check engine light come on? If so maybe you can pull the codes to help isolate the trouble. Many parts stores will loan you one if you don't have a code reader of your own.
Intermittent cut out above 3K rpm 99burb [Expired Topic]
1999 Chev 'Burb. K-1500 5.7L/4L60E/3.42 rear. 82,000 miles.
Replaced the 2bolt main in my burb last month with a 4 bolt re-man as the old engine had spun a rod bearing. New engine dropped in easier than pulling the old one. Now has 850 miles on engine. Replaced Engine, radiator, waterpump, All filters, exhaust with shorty headers (edelbrock), all gaskets on intake were replaced, all hoses including heater hoses up to the split for rear/front, clamps, battery cables to engine were fabricated from 0 gauge welding cable(aux cable fine and not replaced), new coolers, chrome valve covers. Engine painted Chevy orange (can't stand a black small block. Besides I grew up with Tonowanda built small blocks). About the only thing I didn't replace was probably the flywheel.
ANYWAY. Had an Electrical problem last week where it cut out and died. T/S it and found the Connection on the PCM had come loose, and the Crank Posit Sensor(CPS) had died. Cleaned the contacts-reconnected the plug to the PCM and replaced the CPS. No SES light(Good). Runs great except when it hits just above 3000 and it cuts in and out, spits out thru the intake, bucks like a mad bull, and the tach goes wacko. As soon as I drop the revs, it reverts back to normal/
Haven't gotten into it yet, but I'm thinking possibly Plug wires arcing (they shouldn't as I replaced them with the engine and routed them exactly as the old ones.). or the coil/ignition module is acting up. I did the testing per Haynes manual for checking the coil, ign. mod., wiring, prior to getting to isolating down to the CPS. Everything checked out ok. No burns or rub marks on the plug wires. I have corrugated split loom tubing on all wires from end to end. No melting or evidence of burning near the Edelbrock shorty headers. Resistance is within spec for each wire. Distributor cap and rotor are new.
Fuel pressure is 63 with engine off and 55 with engine running. New fuel filter, air filter, PCV Valve, pulling 18" vacuum at idle and 21"@2000. Compression is equal @ 165-170 across the board. No valve taps, oil leakage on to any wiring. All connections are tight and verified by VOM.
Anyone got any other ideas??? Thanks.
Larry
Replaced the 2bolt main in my burb last month with a 4 bolt re-man as the old engine had spun a rod bearing. New engine dropped in easier than pulling the old one. Now has 850 miles on engine. Replaced Engine, radiator, waterpump, All filters, exhaust with shorty headers (edelbrock), all gaskets on intake were replaced, all hoses including heater hoses up to the split for rear/front, clamps, battery cables to engine were fabricated from 0 gauge welding cable(aux cable fine and not replaced), new coolers, chrome valve covers. Engine painted Chevy orange (can't stand a black small block. Besides I grew up with Tonowanda built small blocks). About the only thing I didn't replace was probably the flywheel.
ANYWAY. Had an Electrical problem last week where it cut out and died. T/S it and found the Connection on the PCM had come loose, and the Crank Posit Sensor(CPS) had died. Cleaned the contacts-reconnected the plug to the PCM and replaced the CPS. No SES light(Good). Runs great except when it hits just above 3000 and it cuts in and out, spits out thru the intake, bucks like a mad bull, and the tach goes wacko. As soon as I drop the revs, it reverts back to normal/
Haven't gotten into it yet, but I'm thinking possibly Plug wires arcing (they shouldn't as I replaced them with the engine and routed them exactly as the old ones.). or the coil/ignition module is acting up. I did the testing per Haynes manual for checking the coil, ign. mod., wiring, prior to getting to isolating down to the CPS. Everything checked out ok. No burns or rub marks on the plug wires. I have corrugated split loom tubing on all wires from end to end. No melting or evidence of burning near the Edelbrock shorty headers. Resistance is within spec for each wire. Distributor cap and rotor are new.
Fuel pressure is 63 with engine off and 55 with engine running. New fuel filter, air filter, PCV Valve, pulling 18" vacuum at idle and 21"@2000. Compression is equal @ 165-170 across the board. No valve taps, oil leakage on to any wiring. All connections are tight and verified by VOM.
Anyone got any other ideas??? Thanks.
Larry
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Well after 5 weeks of pulling my hair out(I'm 1/2 bald now), banging my head against the walls (I now have 2 door openings, and a window where I don't need them :^)....) a new fuel pump, fuel pressure regulator, I finally figured out what was wrong. I replaced most of the sensors, wires, plugs , cap, rotor, wires, fuel filter, etc. when I changed the engine 2 months ago (350 Reman).
It FINALLY threw a code y'day, so today I took it down to Autozone today and plugged it in. P0339 code. "Crankshaft Position Sensor, Circuit intermittent." I was this close to putting it in the shop for full diagnostics @ $70 an hour...
Got home, pulled out the schematics for the engine and opened up the wiring harness from the Crank Sensor back to the main loom. Disconnected the Computer and ran continuity checks on the wires to the Crank sensor. The sensor signal return wire was flaky, and the 12V line was pinched near the loom ground. Found the faults in both lines, cut and spliced with a bare butt connector, solder, and two layers of shrink tubing. Looked at the connector for the sensor and found the 12V lead clip was NOT making full contact. The tension leaf was pushed up into the wall of the connector. Used a sewing needle to reset the tension leaf so as to make good contact. Re-wrapped everything in tape, split loom and zip ties. Re-connected everything, and started it up.
No surging, no popping,spitting, backfire, miss or anything else. Runs like a bat out of hell. All the way up to 5000 and shifts nice and firm.
Even managed to give a kid in his Nagasaki Rice Rocket Civic :lol: a shock off the line and up to about 60 (when I backed off to turn in to my community). All I saw was headlights getting smaller.
Larry
It FINALLY threw a code y'day, so today I took it down to Autozone today and plugged it in. P0339 code. "Crankshaft Position Sensor, Circuit intermittent." I was this close to putting it in the shop for full diagnostics @ $70 an hour...
Got home, pulled out the schematics for the engine and opened up the wiring harness from the Crank Sensor back to the main loom. Disconnected the Computer and ran continuity checks on the wires to the Crank sensor. The sensor signal return wire was flaky, and the 12V line was pinched near the loom ground. Found the faults in both lines, cut and spliced with a bare butt connector, solder, and two layers of shrink tubing. Looked at the connector for the sensor and found the 12V lead clip was NOT making full contact. The tension leaf was pushed up into the wall of the connector. Used a sewing needle to reset the tension leaf so as to make good contact. Re-wrapped everything in tape, split loom and zip ties. Re-connected everything, and started it up.
No surging, no popping,spitting, backfire, miss or anything else. Runs like a bat out of hell. All the way up to 5000 and shifts nice and firm.
Even managed to give a kid in his Nagasaki Rice Rocket Civic :lol: a shock off the line and up to about 60 (when I backed off to turn in to my community). All I saw was headlights getting smaller.
Larry
lol!Used a sewing needle to reset the tension leaf so as to make good contact.
Sometimes it's the simpliest thing! Glad to see that you got it running smooth!1 - 4 of 4 Posts
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