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Joaa
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Dec 18, 2013, 6:41 AM
Post #1 of 16
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96 blazer no start
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96 blazer 4.3 vortec has 55 psi fuel pressure no codes stored
Will not start unless I spray carb cleaner into it first then it runs normal
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Hammer Time
Ultimate Carjunky
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Dec 18, 2013, 6:52 AM
Post #2 of 16
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Re: 96 blazer no start
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55PSI is too low for an engine that isn't running. You're likely going to need a fuel pump.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Dec 18, 2013, 6:56 AM
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Re: 96 blazer no start
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No codes? Hmmm - may think it's all warmed up already. There should be a coolant temp sensor for the computer right at/near thermostat (yellow and a black wire and plugs in) that sends info passed thru it to act as a choke. Ohms on the thing should change from stone cold to hot. Lost my chart but if it doesn't it's not working - should have a code??
Other is the plug may be lousy/dirty/corroded. This just one guess of several possible things. Did you do a comprehensive fuel pressure test and it holds OK? Vortecs are sensitive. 55 fine. Below 48 +/- it won't start and might not run,
T
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Tom Greenleaf
Ultimate Carjunky
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Dec 18, 2013, 7:15 AM
Post #4 of 16
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Re: 96 blazer no start
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My mistake. Sorry. It needs more pressure. Spec and test should be as follows if not wrong itself .................
TESTING
- Turn the ignition OFF for 10 seconds.
- Attach fuel pressure gauge J 34730-1A or its equivalent and relieve the fuel system pressure. Wrap a shop towel around the fitting while connecting the gauge to prevent spillage.
- With the gauge still attached, turn the ignition ON but not start the engine. The pump should operate for 2 seconds.
- Bleed the air out of the gauge into a suitable container.
- Turn the ignition OFF for 10 seconds.
- Turn the ignition ON but not start the engine.
- Monitor the fuel pressure with the pump running. The pressure should be 60-66 psi (415-455 kPa).
- ~~~~~~~~~~~~~~~~~~
T
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Joaa
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Dec 18, 2013, 9:17 AM
Post #5 of 16
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Re: 96 blazer no start
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I talked to the mech. That checked
It for codes earlier he said there eas
A code for a small vac leak and he meant
He had cleared the codes. I had noticed
a gas smell before but only on tight corners
On my way to buy my own code reader right now
I think he was trying to manuver me into his
shop. sneaky huh. |
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Hammer Time
Ultimate Carjunky
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Dec 18, 2013, 9:24 AM
Post #6 of 16
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Re: 96 blazer no start
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The code reader isn't going to increase your fuel pressure.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Dec 18, 2013, 9:29 AM
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Re: 96 blazer no start
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If you catch this don't go buy the super cheap code reader but see if at least the level of like and Auntozone will read codes for you. Cleared codes may/could take a while.
Sorry I was 10lbs off on pressure - alone that would run lousy if at all if you believe the 55 PSI noted and if it even jumped up probably notice a general lack of proper power or not running as well is it should. Needs to have all things taken in to blame what. Codes are clues and do not plain tell you part "X" is the problem but rather the circuit that involves it.
If you don't like that shop find another. You don't want to be wrong with the fix and a fuel pump I suggest an entire whole GM unit which is more expensive IF THAT IN FACT IS THE CONCLUSION of the problem and the fix - think it is so far.
Good luck. If too late don't freak if a cheap code reading doesn't show anything if just reset especially,
T
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Joaa
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Dec 18, 2013, 6:30 PM
Post #8 of 16
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Re: 96 blazer no start
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I bought the code reader 265.00 the guy at a/z said 55psi was enough and the gas smell is what I should be finding.
It will smoke the tires and has pkenty of power once it starts so I cant see it being a fuel pump problem.
The plan is to drive it around an hour or so and hope a code comes up again. Also check into the temp sensor.
It has 116,000 miles on it and in great shape so I suppose its nickle dime time to start
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Hammer Time
Ultimate Carjunky
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Dec 18, 2013, 6:49 PM
Post #9 of 16
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Re: 96 blazer no start
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You need to understand one thing. The people on this site are certified, professional technicians. The people at Autozone are pimple faced kids working part time selling parts with no technical training at all. I do this for a living and I am telling you that your fuel pressure is too low. If you don't care to listen, that's not a problem, we can move on to help someone else.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Dec 18, 2013, 10:36 PM
Post #10 of 16
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Re: 96 blazer no start
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Quote">>I bought the code reader 265.00 the guy at a/z said 55psi was enough and the gas smell is what I should be finding.<<"
Say what!? AZ is good about taking things back most of the time. A code reader is NOT going to tell you where or what smells like gas and their own (AZ) parts site leads to the pressure specs. The people at parts outlets of any brand are there to sell parts. Plenty of customers come in not knowing what they need. It doesn't work well that way not much different than grocery shopping, go and tell them you are out of food and let them decide what you should buy?
This may still have plenty of power once running - no two are going to behave exactly the same. Pressure you were told is too low to be it's best. Fuel odor is probably either a leak or burning so much you smell it from the tailpipe? Gotta look around for a leak or since corners matter even the gas cap.
Forget the coolant sensor and being nickel dimed as some things like that usually last forever.
Back to fuel odor: Is this rusty at all? Fuel filter, fuel lines and gas tank and anything to do with it are highly likely to rust to leaking. Gas tanks leak at seams and on top out of sight, filler necks exposed if so and any lines going to and from it.
Get a real diagnosis and this thing hoisted to find the fuel leak or whatever it takes. Fuel pressure needs to be verified as for now I don't believe findings were accurate.
Note: Hard codes will come right back after a reset and light the check engine light. If intermittent could take some time. Codes are not telling you of a vacuum leak either just with certain codes that would be on the list of things to rule out or fix,
T
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DanD
Veteran
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Dec 19, 2013, 5:45 AM
Post #12 of 16
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Re: 96 blazer no start
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Sitting back reading this thread I thought I'd throw in my 2 cents.
Ten to one the "small vacuum leak" is a EVAP leak probably a P0442?
And like the other's have said you need to find this leak before any other diagnostics are performed.
The 55psi fuel pressure you're talking about is likely after it is running which is the bare minimum to keep the thing running without any noticeable issues.
But what's the pressure during cranking; maybe 45 or 50?. Battery voltage during cranking is likely around 10 volts. You already have a weak pump that during cranking and this lower (normal) voltage, just isn't cutting it to open the popit style injectors. If the injection system in your vehicle is still the original design from the factory; they are not opened electrically. They are mechanical injectors that need fuel pressure to open; much like the old diesel injectors.
Yes it might run fine, but that's with the charging system bringing the voltage back up to around 13.5 volts. More voltage the pump spins faster making more pressure.
Before replacing the pump I would perform a voltage drop test on the power feed to the pump. If it's less then a 1/4 volt we know the fuel pump is receiving proper voltage. Wouldn't hurt to check the ground side of the circuit as well; same spec.
Now if you still feel that the fuel pressure is good enough; you have one other option. There is a retro fit injector system that GM brought out to fix a sticking popit valve issue. It changes the mechanical injector valves to the newer style electric injectors. There's no changes that have to be made to the electrical system; you just pull the old system out and the new fits right back in; but it's not cheap. Probably more then a fuel pump change and it's sold at the dealer parts counter.
One last thing, using starting fluid on a gas engine is play with fire. One of these times you're going to either blow the exhaust or the oil pan off of this vehicle.
Dan.
Canadian "EH"
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Joaa
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Dec 19, 2013, 7:03 PM
Post #13 of 16
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Re: 96 blazer no start
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I went to the chevy garage and got into their books today. Fuel pressure ignition on engine off 60 to 66 running 50 to 63 with return line briefly restricted 66 psi. I guess everyone was semi right anyway.
I got the resistance test parameters for the coolant sensor and found mine to be way out of whack. I changed it and its working fine.
Thanks for the input guys between your help and 35 years as a big rig mechanic I was pretty sure I could fix it
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Hammer Time
Ultimate Carjunky
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Dec 19, 2013, 8:10 PM
Post #14 of 16
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Re: 96 blazer no start
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I'm betting that your problems aren't resolved yet.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Dec 20, 2013, 1:18 AM
Post #15 of 16
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Re: 96 blazer no start
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Quote">>I got the resistance test parameters for the coolant sensor and found mine to be way out of whack. I changed it and its working fine.<<"
OK - those allow so many ohms thru them given the temp. I've tested suspect ones on a stove with exacting known temps and VERY few were really bad. Hard to get a good connection to the prongs at that sensor without a spare pigtail.
Not the point now totally as it did demonstrate some low fuel pressures - right? That could be intermittent. Intermittent for coolant temp sensor would more likely be the connection or wiring to and from it IMO.
As HT said, I'd expect the problem is not fully fixed yet,
T
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Tom Greenleaf
Ultimate Carjunky
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Dec 20, 2013, 1:23 AM
Post #16 of 16
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Re: 96 blazer no start
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OK, if this shows it's a fairly generic chart for GMs anyway. Thing needs to change with the temp it's exposed to as said earlier. Never known one to change and be wrong so rarely needed to know/compare exact values.........
Take that with a grain of salt. Chance that it's not precise for each GM vehicle but the general idea,
T
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