Fuse Box Needs a tap with a mallet to start

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JoeChasko
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Joined: Fri Jan 29, 2016 12:41 pm

Fuse Box Needs a tap with a mallet to start

Unread post by JoeChasko » Fri Jan 29, 2016 12:43 pm

My student-teaching daughter has a nice black 2005 Saturn Vue AWD with a little problem. Once in awhile, more often in afternoon sun, it cranks full bore but never catches until it sits for 30-90 minutes, or you have it towed.

There is no fuel smell, and no plug wires so I can't do a spark check like I did in the '80s. It will start happily for weeks at the repair shop without malfunctioning, but one time, a guy in a parking lot says to pop the hood, and raps the big fuse & relay box under the hood with pliers. Vroom!

I pulled the top from the box and swapped the fuel relay with another identical one, and the fuel fuse is fine. It failed as soon as I put the top back on the box, but the rubber mallet got it going. The box does not seem to split or R&R without a lot of work. Since I didn't smell fuel I didn't swap the ignition relay.

She just pops the hood and taps the E box with the mallet now and then. It starts every time, and she says she hears a ding near the grill.

A reliable, though not resalable solution. Any ideas?

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm

Re: Fuse Box Needs a tap with a mallet to start

Unread post by carriedi » Fri Jan 29, 2016 9:21 pm

that's tough because you have to check the car when the problem is acting up. When the car won't start you have to see where you have lost either battery voltage or pcm battery voltage or pcm reference voltage. Some where, something is missing. then Tap on the fuse box and see what turn back on.
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JoeChasko
Posts: 2
Joined: Fri Jan 29, 2016 12:41 pm

Re: Fuse Box Needs a tap with a mallet to start

Unread post by JoeChasko » Tue Feb 02, 2016 8:10 pm

That's helpful. Just touch all the fuses for ecm, pcm, ignition, and injection. Now I just have to catch it!

Basic question - is injection like a carb, that no fuel smell means we are getting no fuel? I smell none at the exhaust, even after cranking for a full minute. So that suggests PCM (ECM) voltage or malfunction?

My daughter hears a little ding when she taps the box (I can't hear it) that sounds near the grill to her. Mean anything?

BTW, no Engine codes ever.

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carriedi
Posts: 2573
Joined: Wed Apr 10, 2013 12:42 pm

Re: Fuse Box Needs a tap with a mallet to start

Unread post by carriedi » Wed Feb 03, 2016 3:43 am

If you have a good fuel injection pulse without spark, yes you can flood the engine with gas just like a carb. But, you can check for fuel pressure, injector pulse and spark when you crank the engine.

to test the spark on the four cylinder, with the coil pack on all four cylinders, take the coil pack off and run spark plug wires over to the plugs. You can unplug the coil's connector and take the coil off the engine. Once the coil is off the engine, plug the connector back on and lay the coil on the engine upside down. Then run spark wires from the coil to the spark plugs. then you can check the spark for each cylinder.

Test for fuel pressure and injector pulse first. If you don't have fuel pressure or injector pulse, spark won't make any difference.

Tapping on the fuse box to make it start sounds like you don't have power through the fuse box. Bad fuse box, bad connection, bad relay inside the box. But you have to see what's not working in the curcuits to find out where the problem is.
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