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Tahoe would crank, not start, 3rd time it started, on a hot day.
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gezeichnet
User
May 15, 2016, 7:41 PM
Post #1 of 4
(1075 views)
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Tahoe would crank, not start, 3rd time it started, on a hot day.
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It appears that this is a classic fuel pump problem, but I'm not sure if it is related to the brushes on the pump motor being warn.
It is suggested that when it doesn't start, I could whack the gas tank with a rubber mallet, which will get it going, however this is obviously not a long term solution.!
A local mechanic agreed with me, however he suggested something to me which I never heard. He said to buy a quart of ATF fluid and put it in the gas tank, and that will lubricate the fuel pump better and pro long its life. I'm and older guy and former racing mechanic and that suggestion strikes me as nonsense and will probably foul the spark plugs.
But, I am never too old to learn. What do you mechanics think of this ATF suggestion?
At any rate, I have never had this problem before and wonder whether I can get the fuel pump tested. I am told you need a shop with an Ocilloscope. Is this a common piece of equipment
in auto shops?? Of course, I don't want to neglect a fuel pump problem because you ain't going anywhere without fuel!
Your thoughts please.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 15, 2016, 8:23 PM
Post #2 of 4
(1069 views)
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Re: Tahoe would crank, not start, 3rd time it started, on a hot day.
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If the commutator and brushes are worn out in the pump, ATF in the gas tank isn't going to fix that. If hitting the fuel tank gets the pump to come on, it needs a fuel pump. Eventually it is going to get you stuck somewhere if you don't address it soon. I really don't think putting oil in the fuel tank would be good for the catalyst and O2 sensors.
I wouldn't rely just on a fuel pump current ramp waveform to condemn a pump. Current ramping is great for determining pump rotational speed and how much current the pump is using, but the shape of the waveform can be easily misinterpreted.
When you go to replace the pump make sure that you inspect the bottom of the tank for debris. That is the #1 pump killer. If feasible, drain the tank and wash it out with soap and water. Then let it dry out in the sun.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 15, 2016, 8:25 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 16, 2016, 12:19 AM
Post #3 of 4
(1061 views)
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Re: Tahoe would crank, not start, 3rd time it started, on a hot day.
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Listen to DS.
One comment from me: Don't put a quart of ATF in fuel tank! Quit listening to whoever suggested that for mechanical help,
T
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gezeichnet
User
May 16, 2016, 9:00 AM
Post #4 of 4
(1046 views)
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Re: Tahoe would crank, not start, 3rd time it started, on a hot day.
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Thank you all for your responses. I declined to put in the ATF as it made no sense to me either.
As for the pump, it is being replaced today. Truck has 137,000. miles. I figure it is entitled to have a new fuel pump and good for my peace of mind.
Also appreciate your opinion on the oscilloscope.
Thanks
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