89 3.0 hard to start when cold
03-16-2008, 05:21 PM
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89 3.0 hard to start when cold
Need help
replaced plugs,cap,wires,rotor,coldstart valve,starter,fuel pump,air filter,fuel filter,,battery,terminals,water pump,heatercore,belts,hoses,idler pulley, still takes about 10-15 seconds to start when cold below 30 degrees after first start when warm starts fine.
replaced plugs,cap,wires,rotor,coldstart valve,starter,fuel pump,air filter,fuel filter,,battery,terminals,water pump,heatercore,belts,hoses,idler pulley, still takes about 10-15 seconds to start when cold below 30 degrees after first start when warm starts fine.
03-16-2008, 05:28 PM
#2
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Any check engine lights? I've heard of cracks in the exhaust manifold causing a similar issue on the 22RE motors. Might check yours. Sounds like it could be an issue with the MAF sensor (or equivalent).
03-16-2008, 08:09 PM
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Cold start valve? I assume you mean the injector. There is a timing switch for the cold start injector. It senses the temp of the coolant and the ECU reads that by resistance and voltage. The R/V reads low under a certain temp signaling the ECU for CS injector pulse. If the timing switch is faulty (reading high R/V all the time), the ECU doesn't get a correct reading no matter the coolant temp and won't fire the CS injector. So, no cold start.
Your switch is on the back of the lower intake manifold. It has a big connector....probably black, sits second from left as your facing the engine, and right next to the coolant hose in the middle. It may just need cleaning. And....hehe...it may not be your problem, but it's the first place to look.
Post up if you don't find it.
Your switch is on the back of the lower intake manifold. It has a big connector....probably black, sits second from left as your facing the engine, and right next to the coolant hose in the middle. It may just need cleaning. And....hehe...it may not be your problem, but it's the first place to look.
Post up if you don't find it.
03-16-2008, 08:34 PM
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03-16-2008, 08:44 PM
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I would first check the thermal switch for the cold start injector and then check fuel pressure at the fuel rail prior to a cold start. You may have low fuel pressure caused by a hanging injector or a faulty fuel pressure regulator. The pressure regulator should hold and maintain fuel pressure for a given period of time making it easier to start the vehicle after its been sitting awhile. It takes time for a fuel pump to rebuild the necessary pressure lost to this device if it's faulty. Depending on the severity of the damage your vehicle may never operate at a correct fuel pressure. Just for the heck of it, the next time you get done driving your truck for the day, clamp off the return line between the regulator and the tank and see if it starts easier in the morning.
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03-16-2008, 08:57 PM
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I would first check the thermal switch for the cold start injector and then check fuel pressure at the fuel rail prior to a cold start. You may have low fuel pressure caused by a hanging injector or a faulty fuel pressure regulator. The pressure regulator should hold and maintain fuel pressure for a given period of time making it easier to start the vehicle after its been sitting awhile. It takes time for a fuel pump to rebuild the necessary pressure lost to this device if it's faulty. Depending on the severity of the damage your vehicle may never operate at a correct fuel pressure. Just for the heck of it, the next time you get done driving your truck for the day, clamp off the return line between the regulator and the tank and see if it starts easier in the morning.
Any of those issues would also create problems starting when warm and during operation.
03-16-2008, 10:03 PM
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As far as problems with warm starts and warm engine operation, It is not uncommon for any fuel injected vehicle to have one or more injectors leak down over time. Some leak down faster than others. A slow leak down from an injector while the vehicle is turned off may go completely un-noticed by the driver on a re-start as it could be a minimal pressure drop that can quicky be compensated for if the fuel pump and regulator are both working correctly. I am talking about few tenth's of a pound per hour, which can add up significantly overnight, but not cause any type of noticable drivability concerns.
The guy states he is having a problem with cold starts and cranking times that exceed 10-15 seconds. If he is leaking down then how can one expect the cold start injector to have the necessary fuel pressure behind it to operate correctly when it feeds off the same rail as the other injectors. I am not saying that the temp sensor is not the problem, but it is more that reasonable to suspect low fuel pressure in the fuel rail of much older vehicles as they sit for hours, days or weeks.
Let your truck sit for a few hours or days with a pressure gauge on the rail and I guarantee you'll notice a drop in pressure. Maybe significant, maybe not, but it will go down and reduce your start time.
My suggestion is to check the Thermal Time Switch and if it is good then block off the return line before your next cold start and see what happens. It's free.
Last edited by mr_schuster; 03-16-2008 at 10:08 PM.
03-16-2008, 10:29 PM
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The x=y was for the OP's reference....sorry...in case the OP didn't know.
And, you have a damn good point. I'd not thought of that.
And, you have a damn good point. I'd not thought of that.
03-20-2008, 03:35 PM
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ended up being the thermal switch= cold start timing switch. 120 @ yota gararge, 8.00 at yard. 4 min fix 4 months of pain and suffering. works great thanks for the help!!!
03-20-2008, 03:54 PM
#13
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Thermal switch = cold start timing switch,To each their own.
As far as problems with warm starts and warm engine operation, It is not uncommon for any fuel injected vehicle to have one or more injectors leak down over time. Some leak down faster than others. A slow leak down from an injector while the vehicle is turned off may go completely un-noticed by the driver on a re-start as it could be a minimal pressure drop that can quicky be compensated for if the fuel pump and regulator are both working correctly. I am talking about few tenth's of a pound per hour, which can add up significantly overnight, but not cause any type of noticable drivability concerns.
The guy states he is having a problem with cold starts and cranking times that exceed 10-15 seconds. If he is leaking down then how can one expect the cold start injector to have the necessary fuel pressure behind it to operate correctly when it feeds off the same rail as the other injectors. I am not saying that the temp sensor is not the problem, but it is more that reasonable to suspect low fuel pressure in the fuel rail of much older vehicles as they sit for hours, days or weeks.
Let your truck sit for a few hours or days with a pressure gauge on the rail and I guarantee you'll notice a drop in pressure. Maybe significant, maybe not, but it will go down and reduce your start time.
My suggestion is to check the Thermal Time Switch and if it is good then block off the return line before your next cold start and see what happens. It's free.
As far as problems with warm starts and warm engine operation, It is not uncommon for any fuel injected vehicle to have one or more injectors leak down over time. Some leak down faster than others. A slow leak down from an injector while the vehicle is turned off may go completely un-noticed by the driver on a re-start as it could be a minimal pressure drop that can quicky be compensated for if the fuel pump and regulator are both working correctly. I am talking about few tenth's of a pound per hour, which can add up significantly overnight, but not cause any type of noticable drivability concerns.
The guy states he is having a problem with cold starts and cranking times that exceed 10-15 seconds. If he is leaking down then how can one expect the cold start injector to have the necessary fuel pressure behind it to operate correctly when it feeds off the same rail as the other injectors. I am not saying that the temp sensor is not the problem, but it is more that reasonable to suspect low fuel pressure in the fuel rail of much older vehicles as they sit for hours, days or weeks.
Let your truck sit for a few hours or days with a pressure gauge on the rail and I guarantee you'll notice a drop in pressure. Maybe significant, maybe not, but it will go down and reduce your start time.
My suggestion is to check the Thermal Time Switch and if it is good then block off the return line before your next cold start and see what happens. It's free.
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