Hard to start 5.7gipmda

I have a 5.7 gipmda that is hard to start. What I have done so far is to take the s terminal off the starter solenoid and turn the key to start. I heard the fuel pump run for 3 seconds or so to prime the fuel. Then I turned it more to crank and did not hear anything. So I reconnected the yellow wire to the starter solenoid and cranked the engine. It took about 10 seconds to start and I noticed when it did start was exactly when the oil pressure built up. Then I took both relays near the low pressure fuel pump and cleaned the connections. I put them back in and for the first time since I have owned the boat(2 months) it started on the first turn of the key. I could only get it to do this twice. Now it still takes 10 seconds of cranking to get the boat running. Does this sound like a relay going or gone bad or something different? Thanks in advance for any help.

Re: Hard to start 5.7gipmda

After you turn the key on, the pumps should run for 2 seconds and shut off. When you start cranking the engine, the ECM has to see a reference signal from the ignition before it will turn the fuel pumps back on.
Only one of those relays is for the pumps, the other supplies power to the injectors.
It could be a relay going bad, or it could be the connector inside the relay sockets are corroded and loose.
Have you done any fuel pressure tests or other troubleshooting?

Re: Hard to start 5.7gipmda

I did not do a fuel pressure test yet. I have ordered a gauge for gm tbi. I haven't received it yet. I will do that as soon as I get the gauge. I have taken off both fuel pumps and checked the screens both were clean as well as the fuel reservoir. The knock sensor that the yellow wire on the starter solenoid is connected to looks pretty old and rusty, could this have anything to do with it? Also once it starts the stream from the injectors is nice and uniform no drips or hesitation. If I want to keep it running I have to keep it at about 1000 rpm if I don't it will stall.

Re: Hard to start 5.7gipmda

How would I check that relay to see if it were bad?

Re: Hard to start 5.7gipmda

The knock sensor that the yellow wire on the starter solenoid is connected to looks pretty old and rusty, could this have anything to do with it?

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HUH????? The yellow/red striped wire going to the solenoid does NOT go to the knock sensor. Should have a dark blue wire going to the knock sensor.

Re: Hard to start 5.7gipmda

Uh oh!

Re: Hard to start 5.7gipmda

bluecollerboater said:

Uh oh!

Click to expand...

Hmmmm I think we might be on track to finding your problems. :facepalm:

Why was the yellow wire on the knock sensor? Got any pictures? Was some work done in that area?

Re: Hard to start 5.7gipmda

No work that I know of. New to me boat though. I will check again tomorrow and try to get some pics. When I was unhooking the yellow wire from the solenoid I was half upside down with a fuel line fitting in my ribcage maybe I am wrong about the yellow wire at the knock sensor. I sure hope so.

Re: Hard to start 5.7gipmda

Don,
You were correct. The wire from the knock sensor was dark blue. The end on the knock sensor was bleached somehow to a pale yellow or cream color. When I followed it back it was dark blue. The yellow wire from the starter solenoid went into a bundle exactly were the knock sensor came out. With the end of the wire being bleached I thought it was the same wire. I bought a. New fuel pump relay today but won't be able to try it until tomorrow maybe. I think don may be on to something with the connectors inside the relay socket, they don't look that great. Unfortunately it looks like the same old story. The previous owner has not done much maintenance. The knock sensor is rusted and so is the coil.

Re: Hard to start 5.7gipmda

So I found the problem it was not the fuel pump relay it was the fuel injector relay directly next to it. I used a wiring diagram for the fuel pump from another post that don put up. So thanks Don s. I appreciate the help. Now to start another post with the next problem!