Vacuum line question

I have a 1990 Dodge Grand Caravan 3.3L. Replaced the fuel pump and alternator in the same week, and now it has extended crank before starting. As part of troubleshooting and trying to figure out what the issue is, I’m also wanting to put some Seafoam into the system and clean things out. On my other cars, I just put it in through the power brake booster vacuum line, but on this car, I don’t know if the power brake booster line vacuum line feeds all the cylinders equally or not. Does anyone know? If not, what vacuum line should I use?

I think you need to get a fuel pressure tester on it to check pressure during extended cranking. Sounds like you may have a sluggish pump, a problem with the check valve, or I suppose its possible to have an injector sticking open. Those would give you low fuel pressure and no start until the pressure built up.

I don’t understand why there would be unequal distribution of vacuum in the cylinders but can’t see it would make much difference anyway. Its not going to fix the problem though.

It doesn’t matter which vacuum line you use; all cylinders will receive a dose of SeaFoam.

As to the delayed starting that could be due to a loss of residual fuel pressure. The system is designed to hold pressure while the car sits overnight, etc and which then allows an instant start.
Most fuel injection pumps have a small check valve in the pump which is supposed to hold pressure from bleeding back to the tank.

If it’s not an iffy check valve then one has to suspect a leaking injector or fuel pressure regulator.

The check valve is essentially a BB and a ball point pen spring with the spring pushing the BB against the ball seat while the the pump is not operating.

Just use a fuel pressure gauge to see what the rail pressure is when running…then leave it on to see what psi it holds. If there is a major drop…there is your problem.

Another way to see if this is the issue is to turn your key all the way on and off several times so the fuel pump can prime the rail. I would do 3 key cycles…do not engage the starter until the 4th try. If you get an instant start after this…you know its the fuel pressure as the cause.


It’s not the fuel pressure. I’ve tried priming the rail and also holding the gas pedal all the way to the floor, neither one works. I’m in the process of replacing the plugs right now. I knew the Seafoam wouldn’t fix the issue, just doing it as part of overall maintenance.

How did you do the “prime the fuel rail” experiment? Since the slow to fire up problem started immediately after the fuel pump was replaced, that puts the fuel system and especially the pump check valve or fuel line pressure leaks at the top of the list of suspects. Slow to fire up is a common symptom of the fuel rail pressure not holding like it should.

I expect you already know this, but when you put a cleaner into the intake manifold, it doesn’t clean the injectors in the same way it would if you put it into the gas tank.

If you think the alternator is the source of the problem, have someone help you measure the battery voltage during cranking. If it stays above 10.5 volts, the slow to crank problem isn’t likely due to the alternator.


I love your user name . . . !

@db4690 Thanks, my name really is Jack. :smile:

I checked the fuel rail just by turning the key on for a few seconds, then off, then on, then off and repeating it 3 times, before cranking. I heard the fuel pump come on each time. I changed the alternator because it had a short in it, nothing to do with the extended crank.

It could be the check valve, but it turned out the issue was mostly a need for new spark plugs. I did them today and now it starts every single time, instead of having to be cranked 3 or 4 times before starting. It does crank maybe 1 or 2 seconds longer than expected, but it’s much better than it was. I don’t think the fuel pressure regulator has any issues… Maybe, but no gas in the vacuum line going to it. I’m gonna put a fuel pressure gauge on tomorrow, and switch out the check valve and see if that 1 or 2 extra seconds to start goes away.

Until then, I’m just gonna spend the night cursing the guy who designed this engine. Had to change 3 plugs and wires from underneath, which required holding my head and shoulders up off the creeper while stretching as far as I could, in order to reach them. Stupid alternator had to be taken out from the bottom, too. Miserable.

Is the check engine light on? If so, do you know what the codes are? If you’re losing your reference signal from the camshaft position sensor, this could cause a vehicle of this era to crank for a long time before starting. I think these engines will start and run without the cam sensor working right but at reduced efficiency.


A modern engine can start with a bad cam sensor, but it usually takes more revolutions, before it starts

It will also stay running if the cam sensor fails while it’s running

cursing the guy who designed this engine. Had to change 3 plugs and wires from underneath

lol … been there, done that. I expect the folks who designed it that way did so b/c they think the owners shouldn’t be working on the car in the first place, and any repairs or maintenance will should be done in a pro-shop with a lift. has a discussion group devoted to the minivans and the Pacifica. I have had two Chrysler Corp. minivans and have found good help at that site.

Good luck and please let us know what you find.

Ok, riddle me this: Engine started every single time, after changing the spark plugs, until the next day, when it returned to it’s ridiculous 3-or-4-extended-cranks-to-start issue. I know it’s been awhile, but I haven’t had the time to go to the mechanic to have him check the fuel pump he put in, because I work 100 hours a week, no joke.

I think it might be the cam sensor, but wouldn’t that throw a code? There isn’t a code for it. It does have some symptoms though; the extended cranking, and a little stuttering right when you first begin driving.

How did the old plugs look?

Normal wear for about 60,000 miles, nothing remarkable.

Maybe there’s a fuel pressure bleed off that is intermittent. That could be due to an iffy check valve in the pump, fuel pressure regulator, or even a single fuel injector hanging open at times
Any of those can cause lack of residual fuel pressure and the cranking time along with stuttering is air being burped out of the fuel lines.

Think of a water hose on a hot day spitting and sputtering until the air is burped out. Same thing.
Not saying that’s the issue; only a possibility.

I changed the camshaft position sensor, and it fixed it, until the next day, just like with the new spark plugs and wires. That makes me think that what is actually “fixing” the cranking issue is the fact that I’m disconnecting the battery to do the labor.

Now, what the heck would it be that causes extended cranking until you disconnect and reconnect the battery? Something obviously getting reset, but I can’t think what it might be.

Computer reset comes to mind, stored values as computer learns are a potential problem. Sensor problem or reflashing the computer with upgrade at the dealer my best 2 guesses. Dealer will fix for $ I am sure.

Does this engine have separate injectors for each cylinder. If so a couple may not be closing entirely when the engine is shut off. When you restart within a few hours, the bad injectors have only had time to release a few drops of fuel into the cylinders and it starts, but over night they have enough time to leak a massive amount of fuel into the cylinders…too much for the next days start up.
Then when you pull the plugs, the fuel has enough time to evaporate and as soon as the plugs are in you can restart it because that extra fuel has evaporated.


Extended cranking can be caused by not enough fuel, or too much fuel. Have you had the fuel pressure checked? If the injectors are leaking that could flood the cylinders. And if the check valve to the tank is leaking, that could cause not enough fuel. In either case, both would show up w/an overnight fuel pressure check.