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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Auto Service Tech
Category: Car
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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My disco runs great, one exception, the first time you..squirt

Resolved Question:

My disco runs great, one exception, the first time you start it, you have to use a healthy squirt of "instant start". Then it will run fine the rest of the day_
Submitted: 6 years ago.
Category: Car
Expert:  GM Tech (Cam) replied 6 years ago.
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I will do my best to assist you. When you are finished please click on accept only if you are satisified. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can.

Expert:  GM Tech (Cam) replied 6 years ago.
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Expert:  GM Tech (Cam) replied 6 years ago.

This is a typically a bad fuel pump. There is a check valve in it that holds the fuel in the lines. I would test the pressure and see it drops off after turning the key off. If so then you likely need a new fuel pump.


Customer: replied 6 years ago.

Sorry, stepped away. yes working on own vehicle. Fuel pressure is about 40 with system off. Stays that way for some time, does not drop rapidly, if at all (have not checked overnight). When ignition hits first click pressure rises to 60psi, then as engine runs it seems to be regulated at 40psi.

Would it be typical for it to be at 40psi in the am before starting? Have not checked that.

I can rent another tester, to attach to the valve on the fuel rail.

Fuel pump was replaced a few years ago by other owner.

When cranking, if pulling a plug and grounding, a spark is seen. If I continue to crank, plug will be wet when I pull it.


Expert:  GM Tech (Cam) replied 6 years ago.

Try in the morning and see if the pressure comes up fast or slow. If slow then wait a bit and cycle the key a few times to see if that builds the pressure before you start cranking.


Customer: replied 6 years ago.

In the morning, The pressure comes up amazingly fast, perhaps a second after the first click on the ignition prior to cranking the engine. Stays at 60psi if I don't crank and cycle on/off at that point. When engine cranks after it starts (when it does) it drops to 40psi, stays that way at idle at up to 4000 rpm, seems to be regulated.

I've been impressed how these little pumps seem to build pressure so quickly, measured at the fuel rail.


With fuel and spark, one would think my chances of starting are good, but there must be a wrong mixture? Once the engine is warmed up, it will start the rest of the day, most of the time 80-90%). That is in the summer now. In the spring/winter it seemed less reliable during the day, needing instant start squirts when engine was cold.


Is this further information helpful in other ideas? or?

Expert:  GM Tech (Cam) replied 6 years ago.

OK, so you have great pressure, possibly too high for starting, but lets move on.

I suspect that you may have leaking injectors or a dirty idle air bypass. I would get your fuel level low and then run some injector cleaner through or have it done professionally at a shop and see what happens.

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