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Cranking Engine for too Long Before It Starts

1-ton

1-ton

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The engine in my truck is not starting up fast enough for me. I have had engines that would start up so easy that I only had to wave my hand at the ignition key to start it, but I am currently having to crank the starter motor on my truck for up to 4 or 5 seconds before it will start.

I am thinking that line pressure is not being held, and the fuel is draining back into the fuel tank. There are a few devices that could be causing this: fuel pump, fuel filter, or fuel solenoid switch.

Fuel filters in a TBI system are supposed to have a valve in them that help maintain fuel line pressure, but I just replaced this only about 100 miles ago, and unless the filter is defective, I cannot see this being the problem.

The "in tank" electric fuel pump should have a valve that holds pressure one-way as well, but if the fuel filter is doing its job, then the fuel pump should not be much of a factor.

The TBI fuel solenoid switch must be working, or my truck would not start. With fuel solenoids, I am assuming they either work or don't work, and there is no "in between", but is there a possibility that there is an "in between", and the fuel solenoid switch is weak and not energizing the fuel system as well as it could?

Any ideas on this?

1991 Chevrolet V3500 Crew Cab 4X4

Engine: 5.7 TBI

Trans: 4L80E
 
[ QUOTE ]
TBI is just like this. My TBI truck is the same way.

[/ QUOTE ]

Damn, that blows! /forums/images/graemlins/doah.gif
 
mine isent, it starts right up, but my mom's(same truck) is a little slow, but not 4-5sec. even with it stiing for a cupple of weeks at a time
 
The only other TBI injected truck I have owned was a 1993 Chevrolet K3500 4X4 Crew Cab Dullie, with a 454, which I bought new off the lot, and I remember it did take a little longer to start than my carbureted trucks, but not as long as the truck I own now.

I am leaning towards the fuel solenoid switch and injectors. I am pretty sure the injectors and solenoid are original with close to 120,000 miles on them, and I can tell, by the way it idles sometimes, that the injectors are dribbling fuel into the intake manifold at low RPM's. If the injectors are not atomizing fuel properly, then this could cause a problem with starting as well.
 
well one way to tell if its line pressure related, just switch the key on, so the pumps run, and then try to start it, if it fires right up, thats the problem, if it doesnt then it could be something else, i had a problem w/ mine not starting right up, but it eventually got to where it wouldnt even start. The temp sensor started sticking to the hot side so it would keep gas away from the motor, thereby keeping it from starting.
 
Does the pump run or not when you turn the key to "run", but don't start it? If it doesn't, your fuel pump relay is likely toast (or that circuit) and if it DOES run, you've got something else going on.
 
A friend of mine with a 1994 GMC 1/2 ton 2wd with a 4.3 V-6 has the same problem--now it sometimes wont start at all unless he gives it a shot of starting fluid--then it fires right up and runs good,usually starts the rest of the day ok(most of the time)--he has had several shops and good techs look at the truck,they replaced a few sensors,ignition module,but no results yet--one guy at the salvage yard he works at told him it has to do with somthing called the "5 second prime curciut"that pressurizes the fuel system when you first turn the key on,he claims there is a wire that always corrodes under the truck somewhere that causes the problem.That guy was driving a ramp truck from the other side of the state dropping off junk cars,we dont know how to reach him for more info--he was in a rush to leave that day--wish I could help him out,I have looked all over his truck and cant see any such wire,but I am from the points and carb era,dont fool much with EFI vehicles.He replaced the fuel pump and relays with no improvement also--. /forums/images/graemlins/dunno.gif
It sounds like this "5 second prime curcuit"could be your problem as well. /forums/images/graemlins/thinking.gif
 
When I turn the key on I can hear the pumps running, but it seems to have about a 1 to 2 second delay between when I turn the key on, and when the solenoid fuel switch kicks in and gets the fuel pump going. I am assuming since my truck does start that the fuel solenoid switch and pumps must be working, or my truck would not start, but is there a possibility of having a weak fuel solenoid switch?

I am pretty sure the temp sensor on my truck is original, and could be causing a problem. I may replace it just because it is so old, but my computer has had no trouble codes though.

I will have to look into that 5-second prime circuit, and see if my truck has one.
 
Doesn't autozone let you use their scanners?

I don't know as I'd trust the temperature gauge at only operating temperature, but if you hooked the scanner up to the truck, you would at least see if it's anywhere near a realistic temperature.

From what I've heard, when the switches fail, it seems to be that they think the engine is warmer than it is, which could cause hard starts.

I don't believe my setup has any delay from key on to pump running, or very little, but if you hear the pump run, the system should be priming.
 
How about unplugging the EST connector and then bumping up the initial timing a few degrees? ..As long as it doesn't have hard starting issues when it gets hot now, i would think a little more timing would make it start up quicker.. I'm doing the same thing with my tpi, trying to get it to start up a little quicker... /forums/images/graemlins/dunno.gif
 
[ QUOTE ]
TBI is just like this. My TBI truck is the same way.

[/ QUOTE ]

So since your TBI engine is like this, ALL of them are? /forums/images/graemlins/rolleyes.gif
The several TBI trucks i have driven didn't take 5 seconds to start.
 
It seems there is a consensus that the temp sending unit could be a likely suspect, so I think I try replacing that. The problem I am having with starting my truck is not a serious one, but I think I could improve how well it starts up if I worked at until I figured it out. Thanks for the responses.
 
If the problem doesn't happen when the engine has been run, then that is one more indication the temp switch is the problem.

If the problem occurs with the engine every time, hot or cold, then the temp switch is likely not the problem.

Friends car (1991) just started hard starting and I'm "helping" him work through it. His, however, never starts easily, and runs fine at all times, but he thinks with a bit less power. TPS and ignition are two things to look at in that case, and with no codes nor idle issues, I suspect it is not ignition related.
 
[ QUOTE ]
If the problem doesn't happen when the engine has been run, then that is one more indication the temp switch is the problem.

[/ QUOTE ]

This is exactly what it does. When my truck has been sitting all night, and the engine is cold, it is harder to start, but after it has warmed up it starts easier.
 
when I had my TBI 350 in my truck, I had this problem, EXACTLY as you describe it. It it turned out to be the fuel pump was dying. My TBI 454 will start on with in a second of bumping the key, at the most.
 
My 87K5 tbi 350 is the same way. Takes about 4 seconds to start up on initial startup, but after its at operating temperatur it only take 1 bump to atsrt it. I never realized this was a problem until you posted. I dont really find it a problem but it does seem kind of weird. I might look into the temp switch. /forums/images/graemlins/thinking.gif
-Harrison
 
My '95 C3500 with a TBI 7.4 does this when you 1st start it. I've found if you crank it over about 5 turns let go of the key and then crank it again it fires right up.
 
another thing you guys need to look into is the oil pressure sending unit. it "shouldn't" allow it to start until a certain amount of oil pressure is built up.
 
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