1999 Chevy Suburban crank no start

1999 Chevy crank sensor Got this call for 1999 Chevy Suburban crank no start yesterday and it happened all of a sudden according to the customer. Customer wanted me to scan it and find out the fix. Got there and hooked my scanner but no communication with his engine computer. This sucks so I ended up checking for sparks and fuel signals from the fuel injectors.

Diagnostics for 1999 Chevy Suburban crank no start

If the scanner won’t communicate with the engine scanner, forget about it as long as it cranks. Just go to the basics: an engine runs because of good compression, spark and good air supply including steady flow of fuel.

Air:

Check the air filter for dirt. If dirty, assume the mass sensor is buggered up because unfiltered air will contaminate the mass sensor wiring elements and it will be worse if the engine is pushing oil. Service the mass sensor if you can and if possible, replace it with OEM part as a maintenance habit in regular intervals.

Spark:

Remove the spark plug and using ST125 spark tester (worth $5); determine the color of the spark. It must be a steady blue color but if you get yellowish or orange color, it means weak ignition. Then you can check the crank sensor or its wires because of it’s high attrition rate.

Compression:

Most engine, this can be done by removing the spark plugs and measuring the compression readings. Must not be lower than 100-120 psi. If lower than 100 psi, expect a jumped timing gear tooth which requires the removal of front timing cover.

Fuel:

Listen for the humming noise of the fuel pump as soon as you put the ignition key on. Should make the pump noise in few seconds and quit after wards. For this type of engine, there is an specific fuel pressure for the fuel pump in order to run. On top my head I figured not lower than 60 psi and you need to replace the fuel pump if lower. Electronically speaking, in this 1999 Chevy Suburban crank no start fuel analysis, get the injector signals if they blink at all using gm noid lights. If not, then the ecm (engine computer) does not see the rpm signal thru the crank sensor and will shut it down.

If it has an accessible fuel control regulator, check it in 2 ways: one with vacuumn hose connected and disconnected. Using the latter, fuel pressure should increase almost 30-40 %. If not, fuel regulator is bad.

Solution for 1999 Chevy Suburban crank no start

Replaced the crank sensor and all is well!

Thanks!

No Comments »

No comments yet.

RSS feed for comments on this post. TrackBack URL

Leave a comment

You must be logged in to post a comment.