99 Jimmy Not Getting Fuel

slednredhead · January 26, 2008

Ok...I just got done fixing a clogged heater core and vacuum leaks, and now my 99 Jimmy won't start. For the last few months I've noticed when its cold it will bog down in the lower gears, but won't stall at an idle or anything. It sat for a few weeks due to lack of defrost and living in freezing temps, but I would still start it every day. After trying to start it (I can hear the fuel pump engaging and shutting off, but havent checked the psi) and crawling underneath it today, I noticed a gas smell by the tank, but no visible leaks. It also smells of gas up front underneath the hood, and won't start with starting fluid. Is there possibly water froze in the lines somewhere? Clogged Filter? Fuel pump, injectors?? I'm about to rip out my hair!!! It's already supposed to go in for ball joints next week!! Any suggestions-the cheaper the better, lol-are greatly appreciated!!!

bobcat5544 · January 26, 2008

If it won't start with starter fluid then your problem is not fuel related. Make sure you check over every connection and gound you disconnected when you did the heater core and the vacuum lines. I would bet somthing my have not gottin reconnected or disconnected mymistake. also pull a spark plug wire and see if you got spark.

slednredhead · January 26, 2008

If it won't start with starter fluid then your problem is not fuel related. Make sure you check over every connection and gound you disconnected when you did the heater core and the vacuum lines. I would bet somthing my have not gottin reconnected or disconnected mymistake. also pull a spark plug wire and see if you got spark.

will do, thanks a bunch..it was running fine for a few days since the heater core and lines were worked on-could something just have come loose?

bobcat5544 · January 26, 2008

It is possible and it does happen. The person that I helped out yesterday had a very odd problem which turned out to be a ground wire to the ABS module that would not allow the rear tail lights to work only when the was running.

Then agian it could be a new problem. In the rule of diag problems if you just did a large repair and new problem happens 90% of the time somthing was missed.

slednredhead · January 29, 2008

Ok here's an update...the Jimmy has spark at the cap on all wires, I could only reach in and check two at the bottom, and one of them is NOT throwing spark...I'm soooo confused...how can it throw spark at the top but not the bottom? Is it possibly just not throwing enough juice for her to start? It has fuel, it has spark...could she have jumped time or threw the chain? Bad coil? Can a coil just be weak? I've never heard of a weak coil-just good or bad...I poured gas down its guts and she still wouldn't start...she wants to..it almost feels like when you mess up a firing order after a tune up-but nothings been touched, it ran fine for a week after I got it back from the shop-but I started to notice everytime I would try and start her up she was getting weaker and weaker until she just wouldn't start...sorry for sounding like some dumbass broad...but this car has me going NUTS!!!

Well any suggestions are great, I think I'm going to go rent a diagnostics...thanks for ur time!!! Hope everyones having a good laugh!!

bobcat5544 · January 29, 2008

Just to clearify. You pulled the wire at the cap that comes from the coil and you had spark. When you pull wires that go from the cap to the spark plugs you have no spark. Correct

slednredhead · January 29, 2008

Just to clearify. You pulled the wire at the cap that comes from the coil and you had spark. When you pull wires that go from the cap to the spark plugs you have no spark. Correct

I have spark at the cap...but not at the bottom of the wire

I used inductive timing light to check the spark...

is it possible for the coil to throw to low of a current to start the vehicle but enough the timing light will pick it up?

My last tune up ~20,000 miles ago

slednredhead · January 30, 2008

Well I'm giving up for now-I'm heading up to Michigans Upper Peninsula for a weekend of snowmobiling-will update when I get back!

slednredhead · February 19, 2008

Ok-she's up and running again...new plugs, wires, cap and rotor-HOWEVER-now it's a pain in the ass to start when it's cold...i was on my eleventh try when she finally started this morning, after pumping the crap out of the gas...it sat for about three weeks-think I have water in my gas?? My fuel injectors dirty?

Westlotorn · February 20, 2008

Vortech engines are very sensitive to fuel pressure.

give it 52 pounds and it starts every time. Drop it to 45 pounds pressure and it will not start at all or starts hard.

Fuel pumps on GM trucks have issues with the power supply harness. The wires overheat and cause low voltage to the pump.

Airtex and Carter both offer these replacement wire harnesses and the newest replacement pumps for your vehicle actuall use a new style harness to eliminate this GM flaw.

Check Fuel Pressure while starting the vehicle. This is the key. A vortech will run on less pressure than it needs to start. Once started the injectors will keep fireing on lower pressure but starting they need a little more to get them going.

Could be a dirty in line filter causing a loss of pressure to the engine.

Check your pressure first, verify that my pressure numbers are correct for your engine.

Don't do a pressure test on these engines by blocking off the fuel return line, it will blow out the pressure regulator.

The pump may be in need of replacement but I would change the in line filter first and then check the wire harness, if wires are black or stiff and brittle right at the point where they tie into your fuel pump you know they have been overheating, change them. Once done with this you should have full battery power at the pump. 12 volts minimum.

Verify grounds on the vehicle, Battery to Engine, Frame and Body. The three components must ground togeather.

Each needs to be a very good clean ground. Battery usually goes to the engine and frame. Body usually is tied to the frame with a copper or aluminum ground strap to complete the ground circuit.

Check fuel pressure. If you dont have 55 or so it won't start. If pressure is low check the pressure relief valve on the fuel rail next.

Check a manual on this, actual pressure needed might be 56 or 48, memory does not recall the number but if you are as much as 5 pounds low a Vortec system will not start at all. If you are above 65 you will blow the pressure regulator.

If all this is fine check bleed down while the pressure gauge is hooked up. When you shut the engine off or stop cranking the starter pressure should hold at first and then very slowly drop off. A good manual gives time for this bleed down also. If pressure drops right away you have a leak somewhere. Memory says pressure should be within 5 pounds of the start point after 10 minutes or so.

If leaking find it. Could be a hose or injector leaking but you have a leak.

The last thing to consider is the fuel pump. If it was not noisy it is probably working properly.

Make sure you flush the tank while you have it off and remove any dirt from inside the tank before installing a new pump.

Always use a new in tank fuel filter on the pump. Everything listed first should be checked and or changed with or without a new pump so you are not wasting your money by doing the low cost items first, you may find out that a 24.00 pressure regulator fixes your problem and save spending 200.00 for a new pump.