Automotive/no-start

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Expert: - 12/16/2010


Question
Hi, Ernie, I hope you can give me an idea as to what the hell is keeping my car from starting! Alright, one morning i leave work and go to start my car,( pontiac grand am gt1, 2002, 3.4 (3400), 4 door) and doesn't start. the starter turned over, but wouldn't start. It is not the notorious pontiac security passlock problem before. Once in a while I've ran into the car not starting for a few tries, but  then it  would start, but this isn't it either! From what I'm being told by different mechanics is that it isn't getting fuel. But here's the kicker, it will start with starting fluid sprayed into the air intake tube, and if done long enough, it will stay running. If left running for awhile, i can shut it off and start it back up with no problems!The fuel pump pressure was like 60 some lbs., it has fuel coming out of the valve by the fuel rail when checked. It has spark, I've had opinions from 3 different  mechanics, its not getting fuel. BUT THEY DONT KNOW WHY!!! Please help! Thank you very much in advance!

Answer
Not having any specific information on Pontiacs (nor on any other GM products other than on some Detroit Diesel and EMD two-stroke Diesels!), I can only suggest one possibility that might be applicable, if your car's fuel delivery system includes a one-way check valve at some point in order to avoid fuel back-flow when the car is parked and shut off.

If there is a check valve in the intake line to the fuel pump, and if that valve is no longer sealing against fuel flow that would drain the supply line, then it could take some time after the pump has been activated before it draws up enough fuel to raise the pressure and refill the delivery system.  Once that has been accomplished, the engine should start and thereafter run normally.  Too, if the valve leak is a slow one and the drain back takes a while, then the car could be shut down and then restarted normally for as long as the supply line maintains a reasonable amount of fuel to let the pump keep its prime.

This is a problem that was most noticeable and aggravating in the days of carburetors and mechanical fuel pumps driven by cam action at the engine; the fuel delivery in such cars was very low when the starting motor was the only thing running the pump while it cranked the engine.  Spraying in ether or other types of starting fluid, or even pouring a SMALL amount of gasoline down the throttle boards usually worked in starting up an engine in such cases as the brief run of the engine was sufficient to pump up the required amount of fuel.

Your car would have a tank-mounted electric pump, I would assume, one that is intended to provide the needed pressure for the fuel-injection system.  Usually, those pumps are mounted quite low in their tanks, both to limit head and to assure cooling by the fuel they pump, but the problem you have could still have its answer here if that pump is high enough, or if your tank runs at low fuel level at those times when the problem occurs, or if - perhaps - there is a leak in the supply line to the pump that allows it to draw in some air above the fuel level in the tank, along with the fuel, reducing the pump's efficiency.  That may also result in fuel starvation problems under high-load as well.

That is my basic first-principles consideration.  Hope it helps!

Regards .... EGK  

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Ernest (Ernie) Kenward

Expertise

The challenges I most enjoy are thoughtful technical questions of a trouble-shooting nature in both electrical, power electronic and mechanical systems, mainly automotive but also machine control and small-machine PLC applications. Please note, however, that I am NOT a walking shop manual! I DO, however, make it a point to have those manuals and other service literature for those vehicles I DO own, and highly recommend that anyone serious about maintenance or modification of their vehicles do the same; MOST of your answers WILL be found there. For that matter, I do NOT go out of my way to acquire shop manuals for any vehicle I do NOT own! That being the case, any general query to me along the lines of "What is the meaning of this code read from the ECU of my 2015 XYZ?" or "Where is the fuse for the windshield washer pump found?" (try your car's electrical distribution panel for a start!) will not go far. What I do offer is a pretty good collection of literature, insights and hands-on experience with 1950s to 1980's Ford products (plus a developing database of information and practice with the Mercedes diesel cars), along with an engineering perspective and the ability to design and implement custom control, electrical and mechanical subsystems for vehicles. For that reason, I am happy to make my thoughts and efforts available to those who are of like mind and/or are seriously making a point of learning about their vehicles. Use the Opportunity to Learn!

Experience

A key skill in my work and hobby pursuits both is STRATEGIC TROUBLESHOOTING. I am a senior instructor in Electrical Engineering Technology at a leading Canadian polytechnic, my areas being Electrical Power and Industrial Control, electrical and electronics design and manufacturing, and AutoCAD and related CAD/CAE software - plus equipment problem-solving and new equipment design and prototyping. Hobby-wise, I have 30-plus years of experience in auto restoration, mostly in electrical and mechanical systems. Ongoing projects include a 1959 Edsel Corsair, my 1978 Ford E250 class-B motorhome conversion, and the care and upkeep of my Mercedes 300CD. My vehicles become engineering test beds for electrical and mechanical upgrades as ideas present themselves. This includes the design and production of circuit boards to restore or enhance features for which no OEM replacement parts are obtainable, or where better specifications or reliability can be had via newer concepts. Regarding the E250 RV conversion, I designed and continue to revise a custom power distribution system, managed by a Programmable Controller (PLC); this has made most revisions as easy as uploading new firmware as I develop it. The "mini" PLC is a powerful device for custom automotive control systems. One good example (there are many) would be the Moeller "Easy Relay"; these offer a wealth of control, monitoring and variable-and-status display options for such projects. A good example project which has worked well is that one for my RV noted above, which has been on the job - revised in firmware only - for a decade now. It is a load management and charging control system to avoid the sulfation-induced early failure that often befalls deep-cycle batteries used in RV power applications. The battery installed in 2003 lasted long enough to more tnan pay for the PLC that contributed to its longer life ... and the PLC will be there for the next battery as well!

Organizations
IEEE - senior member ... past WCC Student Activities; SME - senior member ... past chair, greater Vancouver chapter chair 318; Edsel Owners' Club - have served in various capacities on chapter executive during seventies; have been Power and Driveline resource on the Edsel Owners' Club "E-team" for more than a decade.

Education/Credentials
Graduate of UBC

Awards and Honors
Certificates of appreciation from IEEE and SME for work in student and chapter activities

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