I'm having trouble starting my trailblazer. Will crank good, the fuel pump is new and can hear it when suppose to, new fuel filter, relay and fuses good. But will not start. Mechanic has turned on or started trailblazer when put fuel through throttle or intake, but also has problems figuring out problem because it will start like how mechanic started it. Need help. Could it be the fuel pressure regulator?
Trailblazer won't start good crank new fuel pump
- Thread starter Dnltvr92
- Start date
Tiggerr
Member
Not being an a$$$ but there's gas in the tank correct? Have you verified the pump actually pumps, not just making noise? Pop the line by the filter and make sure? Filter isn't backwards? If all that's ok then regulator would be next thing. Don't remember how the lines are at the regulator, maybe make sure your getting fuel there, if you can get to it easily. Or like I said at the filter. I have had a pump do me that way once. Sounded like it worked but nothing coming through. I've also forgot to put gas back in the tank too lol
Yeah I made sure there was gas, the pump is pumping gas. The connections are good. I will double check the filter lines tho.
It hums then shuts off. The pump works, because the trailblazer can turn on but only when gas is put through intake and then it starts. I think it could also be dirty fuel lines. I don't know what the fuel pressure regulator does but I feel like it could be the problem
I don't have the tool. I need to buy one before I buy the FPR. The problem from how it looks is that there isn't enough pressure or a bad line. Because the fuel pump is new and the filter.
Tiggerr
Member
If the pump is truly good, no leaks, filter correctly installed (can't remember if you can install them backwards on these) The next thing in line between the tank and injectors is the regulator. After that it's fuel rail and injectors. You have no codes? No CEL? Wonder if your getting signal to the injectors....or injector harness. Can't remember if there's a fuse or relay specifically for the injection.
When you say it'll start putting fuel or starting fluid in the intake, does it stay running after that? Or does it die right out?
When you say it'll start putting fuel or starting fluid in the intake, does it stay running after that? Or does it die right out?
Tiggerr
Member
But after you stop putting fuel directly into the intake does it die? Or stay running. Can you drive it?
gmcman
Member
- Dec 12, 2011
- 4,656
That doesn't necessarily mean the pump works. However you said you hear it run then shut off, so it sounds like it's building pressure.Dnltvr92 said:
Why did you replace the pump, same symptoms?
Just curious, disconnect the FP relay and crank the engine for a few seconds. Then reconnect the relay and turn keyboard ON, how many seconds does the pump run?
Tiggerr
Member
Oh ok then that's a totally different story. The fuel is obviously getting to the engine then. How many miles on it? How old are plugs? Have you cleaned the throttle body and reset the PCM?
Does it idle smooth?
Does it idle smooth?
The old pump turned on for less then a second. It was going bad I believe. Right now I'm not by the vehicle. but I've tried before n it was about 2-3 seconds
It's has about 210k and I purchased the car in January. I have never changed them or cleaned the throttle. I have reset it and when it runs it idles smooth.
The car before this problems ran daily. I haven't looked at it either. But sense the car runs when fuel is added the intake, does this mean the pressure is good?
The car before this problems ran daily. I haven't looked at it either. But sense the car runs when fuel is added the intake, does this mean the pressure is good?
Tiggerr
Member
The pressure must be fine if it's running once you get it started. I would start by looking at your plugs/coil boots. New plugs can't hurt, especially if you don't know their age. Use the delco OE plugs. These don't seem to like any other plug. While you do that, run a compression check also while its apart. Where has your temp gauge been reading? How's your fuel milage?Dnltvr92 said:
Oh and pull off the throttle body while your at it and give it a good cleaning. Common issue in these due to the lack of proper PCV system. I use good old fashioned carburetor cleaner on mine. Cuts the gunk quickly and easily.
If you prime the pump (turn key to run wait til pump stops, turn key off) 2-3 times then try to start what happens?
Well it never past the mid marker for the temp so I believe it's good and I haven't really paid attention to the mileage but I would say 250-300 a tank. Yeah I was planning on changing the plugs also
Tiggerr
Member
Should read right in the middle of gauge. Possible your running too cool and have a clogged cat. 250-300 seems a bit low unless that's all city. Mine averages 15.6 combined since ive had it. My wife drove it mostly till this past February and she's pretty heavy footed. Definitely plugs though and a compression check with 210k on it.Dnltvr92 said:
Cranks with no start, Ima going to try a few things already suggested so I'll be awhile before I can reply to more suggestions
Tiggerr
Member
Ziggy
Member
- Feb 8, 2015
- 207
I'm coming at this from a fuzzy memory, but isn't part of the FPR's job to maintain pressure at the engine after the engine is shut off? He said it'll start with a splash of gas at the manifold, and then will continue to run from there, even restarting after shutting off as long as it doesn't remain turned off for too long. Do our trucks have a fuel return line? Possible the fuel rail is losing pressure after the vehicle is shut off, and the pump can't build enough to pressure to sustain the fuel rail when starting the truck?
that was my thinking, the fpr maintains the psi to the rail but the pump has a check valve also. a pressure test could rule that out.Ziggy said:
Ziggy
Member
- Feb 8, 2015
- 207
I'd be curious too, to know what the fuel pressure is doing when cranking. When you turn the vehicle on, the fuel pump comes on, and shuts off when it builds sufficient pressure. You should position your fuel pressure tester in a place that you can observe the pressure as you're cranking the engine. I think coolasice and I are on the same page here, suspecting that you're losing fuel pressure while the engine is cranking. If I'm not mistaken, there is a failsafe in the system which turns the fuel pump off while the vehicle is cranking, and will only allow the pump to restart after the vehicle is running. I could be wrong in that, but it would help explain why the truck will run fine once it is started.
Well guys it has turned on now but I don't know how long. I just put fuel in the vacuum line, I flooded it then took the spark plug off cranked a little to allow it to release fuel. Then turned it on let it sit for awhile like 20-30 minute. I turned it off and went inside then started it again off and on a few times. Don't know how long it's going to last but it's on. Thank you all for all the suggestions😎
fuel pump turns on when there is ignition pulses. Shuts off 2 seconds after the pulses stop.gmcman said: