Real Fix: Too Much Resistance

July 1, 2017

Uh oh, the engine isn’t starting! This is exactly what one customer said to their service writer upon arriving to the shop. As you know, sometimes a minor part can cause trouble, and it may not always be easy to pinpoint. This is when help from fellow Mitchell 1 SureTrack community members can come in handy. Follow this Real Fix to see how the technician was able to get this 2001 Buick Regal GS 3.8L up and running.

Diagnosis

So what happens when you’re not getting DTC codes? You test and go through trial and error. The technician started by connecting a spark tester to all of the spark plug wires, cranked the engine and found a spark was present.

After seeing the plugs were not the issue, he connected a fuel pressure gauge to the fuel pressure test port, again cranked the engine and found no measured fuel pressure. After this, the technician decided to visually check the fuel pump wiring harness, but there were no obvious signs of damage. He disconnected the fuel pump connector and inspected the connector and the terminals—again no sign of damage. 

The technician used a multi-meter to check for a presence of voltage and ground at the fuel pump and cranked the engine. This time there was an absence of voltage. Observing the fuel pump relay while commanding the fuel pump on with a scan tool, the technician found the relay made an audible click. At this point, he used the scan tool to command the fuel pump relay on while using the multi-meter to check for the presence of voltage at the output circuit of relay, and found voltage was present. Finally, he used the multi-meter to measure the resistance of the fuel pump resistor and found the measured resistance was above specifications.

The Fix

After much testing, it was clear that the fuel pump resistor was the issue. It was replaced and test driven to verify the fix.

Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions.  Read the Real Fix in the Mitchell 1 ShopConnection Blog.

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